Workaround mingw breakage

[kevingranade]

Replaced the to_string() call with stringstream operations.
While I was at it, added an official listing of support for various compilers.

[Rivet-the-Zombie]

Great now I can't readily test this because I patched MinGW.

[KA101]

I'll switch it back. Hang on.

[KA101]

Um, it doesn't seem to work: http://pastebin.com/143LJBda

(I'd appreciate someone else testing this as well.)

[kevingranade]

Wow, I have no idea where all that came from, I'm really confused now.

[i2amroy]

to_string() also stops Cygwin from compiling, so hopefully whatever we do to fix this will also fix the Cygwin version.

[KA101]

Could be changing the compiler screwed something up in my local repo: C::B recorded the compiler change as a change to the project file (I declined to save it, but still). That's one of the reasons I'd appreciate others compiling this.

[vache]

I can roll back my MingW patch and pull this and test it when I get home.

[i2amroy]

This fixes the Cygwin version. My bet would be that you screwed up your local somehow KA101 since I'm not seeing any of those errors at all.

[KA101]

Yeah, was a build issue here. Fixed now. Thanks.