[patch] calling convention and def file

Here's a patch that adds the define TIDYCALL in platform.h and to each
exported function.  This lets apps compiling with a different calling
convention (__cdecl, __stdcall, or __fastcall) find the exports in the
tidy .lib. (Note: it defaults to __stdcall for WIN32 and is blank for
everything else)

It also adds a .def file in src/ so any compiler can generate a native
import library for a dll.  As long as new exported functions are
appended to the .def with a new number (and no other pairs are
changed), dlls will keep binary compatibility.  I don't have VC6 so
I'm unable to change the project files (they'll still compile, but the
.def wont be valid for any dlls made).

-- 
Cory Nelson
http://www.int64.org