Log Message:
Update to 1.3.1:

Regression fixes:
 - fixed excessive memory usage issues with diff and strip
 - fixed ssh performance issue on OS X
 - fixed slow calculation of branch heads
 - fixed handling of port numbers in URLs
 - fixed transaction handling exception
 - fixed incoming with graphlog extension
 - fixed slow commit in fetch extension
 - fixed loading of win32mbcs extension

Other fixes:
 - fixed http username handling in acl extension
 - fixed subrepo path joining on Windows
 - allow update --check to cross branches
 - miscellaneous small doc and bug fixes