put every include before every import

A header first pulled in through an imported module's global module
fragment leaves no include guard in the importing unit - macros do not
cross a module boundary - so a later textual include parses it again and
MSVC rejects the redefinition. Redoes the betterRenderer sweep with
placement that stays out of #if blocks, which is where the previous one
dropped <fstream> and broke nvrenderer_d3d12.cpp.

betterRenderer/renderer/source/rt_model.h

@@ -6,9 +6,9 @@
 
 // TSubModel/TModel3d are owned by the simulation core; a forward
 // declaration here would be a second, conflicting declaration.
+
 import eu07.simcore;
 import eu07.glm;
-
 namespace Rt {
 struct IRtModel {
   virtual TSubModel const* Intersect(NvRenderer::Renderable const& renderable,