0028417: Using PRECOMPILED HEADER to speed up compilation time

Use of Cotire tool is introduced for acceleration of CMake builds, by usage of precompiled headers.
CMake option BUILD_USE_PCH is added to enable / disable use of precompiled headers

When precompiled headers are used, additional compiler macros are defined globally in the build system to avoid problems due to different order of included files:
- NOMINMAX is defined on Windows to prevent defining "min" and "max" as macros by windows.h
- STRSAFE_NO_DEPRECATE and _SCL_SECURE_NO_WARNINGS are defined on Windows to prevent declaring functions of standard C library as deprecated by #pragma, and other warnings in system headers
- GL_GLEXT_LEGACY and GLX_GLEXT_LEGACY are defined to ensure that only OCCT's own glext.h is used
- __STDC_FORMAT_MACROS is defined to have standard C print format macros always defined

Code is corrected to avoid conflicts with system headers and in case of compiling together as unity builds (partially):
- Some locally defined variables in TKV3d, TKHLR are renamed to be unique
- Duplicated definitions of macros and global functions are eliminated in TKSTEP
- Useless header WNT_UInt.hxx is removed
- Usage of local variables conflicting with X11 macro is avoided in Draw_Viewer.cxx
- Local variables in AIS_ConcentricRelation.cxx are renamed to avoid conflict with macros defined in windows.h
- HXX files containing code are renamed to PXX or merged with corresponding CXX files.

IVtkTools classes are corrected to avoid compiler warnings disabled in non-PCH builds by inclusion of VTK headers.

Useless pragmas disabling warnings on MSVC are removed

src/IntTools/IntTools.cxx

@@ -377,7 +377,3 @@ namespace {
   }
   return 1;
 }
-
-#ifdef _MSC_VER
-#pragma warning ( default : 4101 )
-#endif

src/IntTools/IntTools_EdgeFace.cxx

@@ -960,7 +960,3 @@ Standard_Integer AdaptiveDiscret (const Standard_Integer iDiscret,
   }
   return iDiscretNew;
 }
-
-#ifdef _MSC_VER
-#pragma warning ( default : 4101 )
-#endif