Loading screen overhaul POC

The loading screen has been significantly changed:
- The background image is now properly picked randomly instead of taking the `textures/logo.bmp` file, prepended by an external program such as Rainsted/Starter.
- The progress bar has been moved from a floating window to a thin green line at the bottom of the loading screen.
- The log window is now hidden by default. It can be turned on by setting `loadinglog` to `true` in `eu07.ini`.
- There is an animated wheel icon on the loading screen, and a trivia text is displayed.

New translation key:
- `"Did you know"`

TODO:
- Load trivia from a separate file.

launcher/launchermode.cpp

@@ -23,9 +23,7 @@ bool launcher_mode::update()
 void launcher_mode::enter()
 {
 	Application.set_cursor( GLFW_CURSOR_NORMAL );
-
 	simulation::is_ready = false;
-
 	Application.set_title(Global.AppName);
 }
 

launcher/launchermode.h

@@ -18,17 +18,13 @@ public:
 	launcher_mode();
 // methods
 	// initializes internal data structures of the mode. returns: true on success, false otherwise
-	bool
-	    init() override;
+	bool init() override;
 	// mode-specific update of simulation data. returns: false on error, true otherwise
-	bool
-	    update() override;
+	bool update() override;
 	// maintenance method, called when the mode is activated
-	void
-	    enter() override;
+	void enter() override;
 	// maintenance method, called when the mode is deactivated
-	void
-	    exit() override;
+	void exit() override;
 	// input handlers
 	void on_key( int Key, int Scancode, int Action, int Mods ) override;
 	void on_cursor_pos( double const Horizontal, double const Vertical ) override { ; }

launcher/launcheruilayer.h

@@ -19,7 +19,7 @@ http://mozilla.org/MPL/2.0/.
 class launcher_ui : public ui_layer {
 public:
 	launcher_ui();
-	bool on_key(const int Key, const int Action) override;
+	bool on_key(int Key, int Action) override;
 	void on_window_resize(int w, int h) override;
 
 private: