Merge branch 'nd/help-commands-verbose-by-default'

"git help -a" and "git help -av" give different pieces of
information, and generally the "verbose" version is more friendly
to the new users.  "git help -a" by default now uses the more
verbose output (with "--no-verbose", you can go back to the
original).  Also "git help -av" now lists aliases and external
commands, which it did not used to.

* nd/help-commands-verbose-by-default:
  help -a: improve and make --verbose default