Add MSVC 12 (2013) to autotest list

git-svn-id: https://pugixml.googlecode.com/svn/trunk@982 99668b35-9821-0410-8761-19e4c4f06640
Fix compilation warning for toolsets where wchar_t == char.

git-svn-id: https://pugixml.googlecode.com/svn/trunk@983 99668b35-9821-0410-8761-19e4c4f06640