0026585: Eliminate compile warnings obtained by building occt with vc14: 'type cast' pointer truncation and 'type cast' truncation

- Class OSD_EnvironmentIterator is removed (not used, and would definitely fail under Windows if tried)
- Methods UserId() and GroupId() removed from OSD_FileNode (cannot be made portable, as there is no integer IDs of user and group on Windows)
- Draw_ProgressIndicator corrected to properly pass address via Tcl
- OSD_File.cxx: local function is refactored to avoid senseless encoding / decoding of results
- OSD_Process::UserId() method removed, as it cannot be made cross-platform (no integer IDs on Windows)
- OSD_Thread: use WinAPI conversion functions to avoid warnings
- OSD_WNT.cxx: recursion counter passed via function argument instead of TLS
- TDF_LabelMapHasher revised to use correct hasher function for an address

src/STEPConstruct/STEPConstruct_AP203Context.cxx

@@ -224,7 +224,7 @@ Handle(StepBasic_PersonAndOrganization) STEPConstruct_AP203Context::DefaultPerso
     Handle(StepBasic_Person) aPerson = new StepBasic_Person;
     Handle(TCollection_HAsciiString) uid = new TCollection_HAsciiString ( orgId );
     uid->AssignCat ( "," );
-    uid->AssignCat ( TCollection_AsciiString ( sys.UserId() ).ToCString() );
+    uid->AssignCat (sys.UserName().ToCString());
     Handle(Interface_HArray1OfHAsciiString) suffix, prefix;
     aPerson->Init ( uid, Standard_True, lname, Standard_True, fname, ( ! mname.IsNull() ),
 		    mname, Standard_False, suffix, Standard_False, prefix );