Sorting and MSVC 2015 fixes

[aslater]

I've got three commits in this pull request:

• 276a207: when sorting by rating or playcount, if two files are tied, break the tie with compareFileName
• 5748744: Get the project compiling in MSVC 2015 Community (I'm not sure whether these were all necessary or if I could've gotten around them)
  ** Add WinMain when compiling in MSVC
  ** Define __iob_func for compatibility with older DLLs
  ** Wrap the declaration of round() in the same preprocessor check as its implementation
• ce00f5f: Make the sort type persistent by storing the sort ID in a new gamelist attribute ("sortid")

How do they look?

Thanks,

-- Adam Slater

[aslater]

Aaand...wrong flavor of markdown; sorry about that.

• 5748744: Get the project compiling in MSVC 2015 Community (I'm not sure whether these were all necessary or if I could've gotten around them)
  • Add WinMain when compiling in MSVC
  • Define __iob_func for compatibility with older DLLs
  • Wrap the declaration of round() in the same preprocessor check as its implementation