Editor: fold the plan library into the tree as modules, drop its own name

The track layout library came in as a subproject of its own -- its own
CMakeLists, its own install and export rules, its own include tree -- which only
made the build harder to follow now that everything else is a module. It is part
of the editor, so it lives where the editor lives.

- editor/plan_*.cppm / plan_*.cpp: the fifteen interface units and twelve
  implementation units, flat in editor/ beside editorTerrain and orthophoto, with
  the plan_ prefix keeping them clear of what was already there (editor/turnouts
  is the preset catalogue, so the geometry is plan_turnout_geometry).
- modules are named eu07.editor.plan_*, like every other module in the tree.
- namespaces move under the editor's own: editor::plan, editor::plan::geometry,
  ::io, ::render. The library's old name is gone from the sources and the docs.
- every moved file carries the MPL header the rest of the tree carries; it had
  none. version.hpp went with the subproject: macros only, and unused.
- the umbrella header is dropped -- nothing imported it.
- the unit tests survive the fold: editor/tests, behind EU07_EDITOR_PLAN_TESTS
  (off by default), compiles the interfaces a second time into a small library of
  its own, because a test can only import modules from a target it links and
  linking the game would drag the whole simulator in. The code under test needs
  nothing but a compiler. 7/7 pass.
- a switch may now be written with two dashes as well: --editor beside -editor.

Builds with clang 22 (-DWITH_BETTER_RENDERER=OFF); -editor and --editor both come
up in the editor on empty ground.

editor/orthophoto.cppm

@@ -17,9 +17,9 @@ module;
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
-#include "maj0sted/editor/tile_cache.hpp"
 
 export module eu07.editor.orthophoto;
+import eu07.editor.plan_tilecache;
 
 export {
 
@@ -39,13 +39,13 @@ class orthophoto_source
   public:
 	struct ready_tile
 	{
-		maj0sted::editor::TileBBox box;
+		editor::plan::TileBBox box;
 		unsigned int texture{0};
 	};
 
 	// default: Geoportal ortophoto on the fine 100 m grid. pass topo config and a coarse
 	// grid zoom (e.g. 1000) for the zoomed-out topographic underlay
-	explicit orthophoto_source(maj0sted::editor::WmsConfig Config = maj0sted::editor::WmsConfig::geoportal_ortho(), int const Gridzoom = maj0sted::editor::TileGrid::kLevel,
+	explicit orthophoto_source(editor::plan::WmsConfig Config = editor::plan::WmsConfig::geoportal_ortho(), int const Gridzoom = editor::plan::TileGrid::kLevel,
 	                           std::string Cachesubdir = "orto");
 	~orthophoto_source();
 	orthophoto_source(orthophoto_source const &) = delete;
@@ -54,7 +54,7 @@ class orthophoto_source
 	// kicks off fetches for the view (capped) and returns every already-uploaded tile that still
 	// intersects it - including ones outside the fetch window, so a zoom cannot blink them away.
 	// tiles still on their way simply aren't in the answer yet; call again next frame
-	std::vector<ready_tile> collect(maj0sted::editor::TileBBox const &View, int const Maxtiles = 400);
+	std::vector<ready_tile> collect(editor::plan::TileBBox const &View, int const Maxtiles = 400);
 	// how many tiles are still being fetched, for the panel to report
 	std::size_t pending() const;
 	// how many tiles gave up after exhausting their retries
@@ -65,7 +65,7 @@ class orthophoto_source
 	struct transfer
 	{
 		std::string url;
-		maj0sted::editor::TileService::DoneFn done;
+		editor::plan::TileService::DoneFn done;
 		bool ok{false};
 		std::vector<std::uint8_t> bytes;
 		std::string content_type;
@@ -73,17 +73,17 @@ class orthophoto_source
 	// methods
 	void worker();
 	// decodes the cached bytes of a tile and uploads them; returns 0 when the image is unusable
-	unsigned int upload(maj0sted::editor::TileKey const &Key);
+	unsigned int upload(editor::plan::TileKey const &Key);
 	// imagery of a given piece of ground never changes, so a fetched tile is kept on disk and the
 	// next session starts with it instead of going back to a service that is slow and flaky
-	std::string tile_path(maj0sted::editor::TileKey const &Key) const;
-	bool load_from_disk(maj0sted::editor::TileKey const &Key);
-	void save_to_disk(maj0sted::editor::TileKey const &Key);
+	std::string tile_path(editor::plan::TileKey const &Key) const;
+	bool load_from_disk(editor::plan::TileKey const &Key);
+	void save_to_disk(editor::plan::TileKey const &Key);
 	// members
-	maj0sted::editor::TileService m_service;
-	int m_gridzoom{maj0sted::editor::TileGrid::kLevel};
+	editor::plan::TileService m_service;
+	int m_gridzoom{editor::plan::TileGrid::kLevel};
 	std::string m_cachesubdir{"orto"};
-	std::unordered_map<maj0sted::editor::TileKey, unsigned int, maj0sted::editor::TileKeyHash> m_textures;
+	std::unordered_map<editor::plan::TileKey, unsigned int, editor::plan::TileKeyHash> m_textures;
 
 	mutable std::mutex m_mutex;
 	std::condition_variable m_wakeup;
@@ -92,7 +92,7 @@ class orthophoto_source
 	std::vector<std::thread> m_workers;
 	std::atomic<bool> m_quitting{false};
 	std::atomic<std::size_t> m_inflight{0};
-	std::unordered_set<maj0sted::editor::TileKey, maj0sted::editor::TileKeyHash> m_failedkeys;
+	std::unordered_set<editor::plan::TileKey, editor::plan::TileKeyHash> m_failedkeys;
 };
 
 // a single WMS image covering an arbitrary box, for views too coarse for the tile grid - the whole
@@ -102,25 +102,25 @@ class wms_image
 {
 
   public:
-	explicit wms_image(maj0sted::editor::WmsConfig Config);
+	explicit wms_image(editor::plan::WmsConfig Config);
 	~wms_image();
 	wms_image(wms_image const &) = delete;
 	wms_image &operator=(wms_image const &) = delete;
 
 	// asks for the given box at the given size and returns the texture currently available, which
 	// may still be the previous box's until the new one arrives; 0 when there is nothing to show yet
-	unsigned int texture_for(maj0sted::editor::TileBBox const &Box, int const Pixels);
+	unsigned int texture_for(editor::plan::TileBBox const &Box, int const Pixels);
 	// the box the returned texture actually covers
-	maj0sted::editor::TileBBox const &covered() const { return m_covered; }
+	editor::plan::TileBBox const &covered() const { return m_covered; }
 	bool loading() const { return m_loading.load(); }
 
   private:
 	void worker();
 
-	maj0sted::editor::WmsConfig m_config;
-	maj0sted::editor::TileBBox m_requested{};
-	maj0sted::editor::TileBBox m_inflightbox{};
-	maj0sted::editor::TileBBox m_covered{};
+	editor::plan::WmsConfig m_config;
+	editor::plan::TileBBox m_requested{};
+	editor::plan::TileBBox m_inflightbox{};
+	editor::plan::TileBBox m_covered{};
 	unsigned int m_texture{0};
 
 	mutable std::mutex m_mutex;