windows: Add modtime implementation
Merge pull request #575 from stinos/windows-modtime

Add modtime implementation for mingw
runtime0.h: Group binary ops by fives.

So one has some chance to convert numeric op code into symbol.
bytes: Implement comparison and other binary operations.

Should support everything supported by strings.
py: Fix base "detection" for int('0<hexdigit>', 16).
migw32: Fix for mingw32 using a preprocessor-unfriendly definition of CLOCKS_PER_SEC

Note that mingw-w64 does not have the problem.
mingw: Add travis build