consistency with 'build_ext' command option.
Changed 'compile()' and 'link_shared_object()' so 'include_dirs',
'libraries', and 'library_dirs' can be lists or tuples.
Catch up with changes in 'gen_lib_options()':
- change how we call it
- added methods 'library_dir_option()', 'library_option()', and
'find_library_file()' that it calls
Added 'force' flag and changed compile/link methods to respect it.
- add 'extra_preargs' and 'extra_postargs' parameters (and use them!)
- added 'compiler_type' class attribute
- respect reordered arguments to 'gen_lib_options()'
Changed those two methods to only compile/link if necessary (according
to simplistic timestamp checks).
Added 'output_dir' to 'object_filenames()' and 'shared_object_filename()'.
now provided (minus the leading underscore) by the ccompiler module.
Fix 'compile()' to return the list of object files generated.
Cosmetic tweaks/delete cruft.
Added 'verbose' and 'dry_run' parameters to constructor.
Changed 'compile()', 'link_*()' to default lists arguments to None
rather than empty list.
Added implementations of the filename-mangling methods mandated by
the CCompiler interface.
Greg Ward