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/longlong.h

@@ -410,16 +410,7 @@ public:
     }
 
         // convert to double
-        //
-        // For some completely obscure reasons compiling the cast below with
-        // VC6 in DLL builds only (!) results in "error C2520: conversion from
-        // unsigned __int64 to double not implemented, use signed __int64" so
-        // we must use a different version for that compiler.
-#ifdef __VISUALC6__
-    double ToDouble() const;
-#else
     double ToDouble() const { return wx_truncate_cast(double, m_ll); }
-#endif
 
     // operations
         // addition
@@ -1085,12 +1076,6 @@ WXDLLIMPEXP_BASE class wxTextInputStream &operator>>(class wxTextInputStream &st
 
 #if wxUSE_LONGLONG_NATIVE
 
-// VC6 is known to not have __int64 specializations of numeric_limits<> in its
-// <limits> anyhow so don't bother including it, especially as it results in
-// tons of warnings because the standard header itself uses obsolete template
-// specialization syntax.
-#ifndef __VISUALC6__
-
 #include <limits>
 
 namespace std
@@ -1108,8 +1093,6 @@ namespace std
 
 } // namespace std
 
-#endif // !VC6
-
 #endif // wxUSE_LONGLONG_NATIVE
 
 // ----------------------------------------------------------------------------