Changes to build with MSVS 2013 Community Edition

Many changes to build with Microsoft Visual Studio 2013 Community
Edition (Visual C++ 2012).

Please note, csPerfThread.hpp and .cpp must be in the src directory for
this build.

You must also make a csound64.lib import library using MinGW pexports
and Microsoft lib.

All "and" and "or" replaced with standard C++ "&&" and "||".

All functions return some sort of value.

unistd.h omitted for Microsoft Visual C++.