Codechange: Add CMake source group for the saveload compat tables.

While at it, fix the not-working OpenGL sub-group.

cmake/MSVCFilters.cmake

@@ -11,12 +11,13 @@ source_group("Network Core" REGULAR_EXPRESSION "src/network/core/")
 source_group("OSX" REGULAR_EXPRESSION "src/os/macosx/")
 source_group("Pathfinder" REGULAR_EXPRESSION "src/pathfinder/")
 source_group("Save/Load handlers" REGULAR_EXPRESSION "src/saveload/")
+source_group("Save/Load handlers\\Compat" REGULAR_EXPRESSION "src/saveload/compat/")
 source_group("Sound" REGULAR_EXPRESSION "src/sound/")
 source_group("Sprite loaders" REGULAR_EXPRESSION "src/spriteloader/")
 source_group("Squirrel" REGULAR_EXPRESSION "src/3rdparty/squirrel/squirrel/")
 source_group("Tables" REGULAR_EXPRESSION "src/table/")
 source_group("Video" REGULAR_EXPRESSION "src/video/")
-source_group("Video/GL" REGULAR_EXPRESSION "src/3rdparty/opengl/")
+source_group("Video\\GL" REGULAR_EXPRESSION "src/3rdparty/opengl/")
 source_group("Widgets" REGULAR_EXPRESSION "src/widgets/")
 source_group("Windows files" REGULAR_EXPRESSION "src/os/windows/|\.rc$")