Remove MSVC6 support.

Don't support this compiler any more, this allows to get rid of tons of
MSVC6-specific workarounds, in particular we can now use Bind() and natural
template functions calls in the library code.

Also remove MSVC6 project and solution files and don't generate them when
bakefile_gen is ran any more (removing the remaining occurrences of msvc6prj
from the bakefiles results in weird bake-time errors, so it's simpler to just
leave them there).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76532 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/valnum.h

@@ -135,17 +135,11 @@ public:
 
     typedef typename BaseValidator::LongestValueType LongestValueType;
 
-    // FIXME-VC6: This compiler fails to compile the assert below with a
-    // nonsensical error C2248: "'LongestValueType' : cannot access protected
-    // typedef declared in class 'wxIntegerValidatorBase'" so just disable the
-    // check for it.
-#ifndef __VISUALC6__
     wxCOMPILE_TIME_ASSERT
     (
         sizeof(ValueType) <= sizeof(LongestValueType),
         UnsupportedType
     );
-#endif // __VISUALC6__
 
     void SetMin(ValueType min)
     {