Catch up with renamed 'platdir' -> 'build_platlib' option in 'build'.
Don't call 'set_final_options()' in 'run()' anymore -- that's now
guaranteed to be taken care of for us by the Distribution instance.
If 'include_dirs' is a string, split it on os.pathsep (this is half-
hearted -- support for setting compile/link options on the command
line is totally lame and probably won't work at all).
Added 'get_source_files()' for use by 'dist' command.
Added code to 'build_extensions()' to figure out the "def file" to use
with MSVC++ and add it to the linker command line as an "extra_postarg".
- rename 'dir' to 'build_dir'
- take 'package' from distribution option 'ext_package'
- take 'extensions' from distribution option 'ext_modules'
- take 'include_dirs' from distribution
Name keyword args explictly when calling CCompiler methods.
Overhauled how we generate extension filenames (in 'extension_filename()
and 'build_extension()') to take 'package' option into account.