ObjectWaterMesh, MinGW and a bunch of bugfixes

Recent changes:

• New ObjectWaterMesh object for small water pools.
• Improvement of build scripts (new variable "g_compiler" in addition to "g_os"), added support of MinGW (engine can be built with it, but the build will not be properly functional; tools are working ok).
• All console variable are now declared in source/engine/EngineConsole.h.
• "manager_create_*" console variables are renamed to "manager_preload_*".
• Fixed mouse scroll handling in Linux.
• Bones visualization mode in ResourceEditor / Viewer.
• Fixed collisions of RagDoll with BodyDummy.
• Fixed "unknown body" bug in physics solver.
• Non-intersectable objects now can be selected by double-click in UnigineEditor.
• 2 samples of LODs usage.
• Object's materials are now handled by the material class.
• A bunch of flags in objects for surfaces (collision, intersection, shadows and so on).

By the way, building Unigine with MinGW on win32 have helped refactoring win32-specific code because GCC is a little bit more verbose than MS VS.