appdata-validate: New completion.
uscan: New completion, thanks to Federico Ceratto
Refactor bts and uscan, since they use common functions
wtf: Hush stderr when db file doesn't exist.
wtf: Don't offer -f if it was already specified.

Submitted-by: Raphaël Droz (modified)
http://lists.alioth.debian.org/pipermail/bash-completion-devel/2013-November/004991.html
wtf: Look for acronym db from /usr/share/games/bsdgames/acronyms too.

Submitted-by: Raphaël Droz (modified)
http://lists.alioth.debian.org/pipermail/bash-completion-devel/2013-November/004991.html
(testsuite): Limit wtf completions to A* to keep expect happier.