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/cpp.h

@@ -58,7 +58,7 @@
    should avoid doing it or provide unique prefixes then) but we have to do it
    differently for VC++
   */
-#if defined(__VISUALC__) && (__VISUALC__ >= 1300)
+#if defined(__VISUALC__)
     /*
        __LINE__ handling is completely broken in VC++ when using "Edit and
        Continue" (/ZI option) and results in preprocessor errors if we use it
@@ -115,7 +115,7 @@
         */
         #define __WXFUNCTION__ (NULL)
     #elif defined(__GNUC__) || \
-          (defined(_MSC_VER) && _MSC_VER >= 1300) || \
+          defined(__VISUALC__) || \
           defined(__FUNCTION__)
         #define __WXFUNCTION__ __FUNCTION__
     #else