update-dockapps.pl: Correctly sort alpha, beta, and release candidate versions.
update-dockapps.pl: Handle earlier versions of dockapps with alternate names.

Some dockapps earlier versions of dockapps, e.g. the recently added wmacpi-ng,
may have different names than the directories they appear in.  This patch adds
the ability to handle this situation by keeping track of the directory for
getting git information and skipping these dockapps when creating the "+date"
versions.
dockapps.db.in: Update wmacpi webpage, add wmacpi-ng.