[StGIT PATCH 0/6] Various contrib/ updates

This series, asside from small fixes, enhance the bash completion to be aware of file status (notably, makes it much more comfortable to refresh only selective files), and introduces 2 new contrib scripts:

- whereas stg-fold-files-from was designed to merge in the current
patch changes from several other patches, stg-dispatch makes life
easier to split a given patch into several other ones (ie. making a
split series out of a monolithic patch).

- stg-show is a RFC/proof-of-concept for a redesign of "stg show",
which calls git-show much more transparently.  This allows to harness
the full power of the git-show command-line without duplicating the
logic in stgit.

I already made heavy use of the scripts in the last days, and I rate them as good candidates for 0.13.1.