Merge branch 'jc/remote'

Merge branch 'jc/remote'

* jc/remote:
  git-push: Update description of refspecs and add examples
  remote.c: "git-push frotz" should update what matches at the source.
  remote.c: fix "git push" weak match disambiguation
  remote.c: minor clean-up of match_explicit()
  remote.c: refactor creation of new dst ref
  remote.c: refactor match_explicit_refs()