PHYSFS_getLastModTime()

[Ryan C. Gordon]

Even though I've already bumped the version in CVS up to 0.1.6, I'm
declining to release an official PhysicsFS tarball just yet, since I've
just added a new API, and need to give it a day or two to stabilize.

John Hall sent in code for PHYSFS_getLastModTime(), which allows you to
determine the last modification date/time of a given file, if possible.

This compiles and runs under Unix (and probably BeOS, but I haven't tried
yet). MacOS Classic and Win32 need to fill in a function to make it
work...right now the library should still work on those systems, but they
won't be able to recover a file modification time.

Hopefully an official 0.1.6 release will come shortly, but I want to see
about getting win32.c and macclassic.c updated first.

--ryan.