win32mbcs: also wrap windows.pconvert()

Use os.path.split() for MBCS with win32mbcs extension.

win32mbcs: look up modules using sys.modules (issue1729) globals()[module] doesn't work for modules inside of packages, such as os.path.

fix memory usage of revlog caches by limiting cache size [issue1639]

keyword: eliminate potential reference cycles from kwrepo - delete kwrepo.commitctx after using the tweaked version - prefer self.hook over repo.hook to avoid nesting Also pass arguments to commit as arbitrary list. Thanks to Simon Heimberg and Matt Mackall for guidance.

convert/cvs: improve error message on unexpected server output.

transaction: fix uncaught ENOENT (issue1724) The opener raises an IOError on errors where transaction expects an OSError.