0022651: Impossible to build OCC as static library due to using Standard_EXPORT instead of Standard_API

All library-specific macros for defining export / import properties of symbols on Windows (like Standard_API, __Draw_API, _math_API etc.) are eliminated.
Common macro Standard_EXPORT is used in all places where it is necessary.

New macro OCCT_STATIC_BUILD is defined for disabling Standard_EXPORT, to be used instead of HAVE_NO_DLL, though the latter is still supported as well (for compatibility).

To allow building OCCT in static mode on Windows after these changes:
- Files OSD_WNT_1.hxx and OSD_WNT_BREAK.hxx are removed; useful declarations are moved to OSD_WNT.hxx
- In the class IVtkVTK_ShapeData, static fields ARRNAME_MESH_TYPES and ARRNAME_SUBSHAPE_IDS are converted to static inline functions
- Global array ChoixRef defined in IntImp_ComputeTangence.cxx is converted to static function returning element of the array by index
- Unused class Quantity_Convert is removed (it had static field accessed by inline method)
- Struct Approx_Data defined in the same way in BRepApprox_Approx.hxx and GeomInt_WLApprox.hxx is made private member of these classes to avoid name clash
- Some C++ files producing no object code are removed
- In NCollection_EBTree.hxx and StdLPersistent_Collectio.hxx, definition of template virtual method is moved to class definition to avoid MSVC linker warnings on unused symbols

src/Blend/Blend_Debug.cxx

@@ -16,26 +16,14 @@
 
 #include <Standard_Boolean.hxx>
 
-#ifndef __Blend_API
-# if defined(_WIN32) && !defined(HAVE_NO_DLL)
-#  ifdef __Blend_DLL
-#   define __Blend_API __declspec( dllexport )
-#  else
-#   define __Blend_API __declspec( dllimport )
-#  endif /*__Blend_DLL*/
-# else
-#  define __Blend_API
-# endif /*_WIN32*/
-#endif /*__Blend_API*/
-
 //*************************************************
 // recuperation des surfaces des conges approximes.
 //*************************************************
 
 static Standard_Boolean Blend_traceDRAWSECT = Standard_False;
-__Blend_API extern void Blend_SettraceDRAWSECT(const Standard_Boolean b) 
+void Blend_SettraceDRAWSECT(const Standard_Boolean b) 
 { Blend_traceDRAWSECT = b; }
-__Blend_API extern Standard_Boolean Blend_GettraceDRAWSECT() 
+Standard_Boolean Blend_GettraceDRAWSECT() 
 { return Blend_traceDRAWSECT; }
 
 //*************************************************
@@ -43,7 +31,7 @@ __Blend_API extern Standard_Boolean Blend_GettraceDRAWSECT()
 //*************************************************
 
 static Standard_Boolean Blend_contextNOTESTDEFL = Standard_False;
-__Blend_API extern void Blend_SetcontextNOTESTDEFL(const Standard_Boolean b) 
+void Blend_SetcontextNOTESTDEFL(const Standard_Boolean b) 
 { Blend_contextNOTESTDEFL = b; }
-__Blend_API extern Standard_Boolean Blend_GetcontextNOTESTDEFL() 
+Standard_Boolean Blend_GetcontextNOTESTDEFL() 
 { return Blend_contextNOTESTDEFL; }