g10: Implement gpg --quick-revuid

* g10/revoke.c (get_default_uid_revocation_reason): New.
* g10/keyedit.c (menu_revuid): Break out creation of uid revocation
into new function core_revuid.
* g10/keyedit.c (keyedit_quick_revuid): New. Selects key and
uid, invokes core_revuid.
* g10/gpg.c (main): Handle --quick-revuid argument.
* doc/gpg.texi: Document --quick-revuid.

This functionality is a counterpart to --quick-adduid, and will be
useful for projects that depend programmatically on gpg to revoke user
IDs (one such example is "monkeysphere-host revoke-servicename").

• Minor re-indentation work.
• Changed a "0 == memcmp" to "!memcmp"
• Removed tests/openpgp/quick-key-manipulation.test from the Makefile. This test needs to be converted to gpgscm.
• Removed example from whats-new-in-2.1.txt because that is generated.

• Signed-off-by: Werner Koch <wk@gnupg.org>