Refactor $WikiPlugin::name and $WikiPlugin::description stuff.

Refactor $WikiPlugin::name and $WikiPlugin::description stuff.

It is best if all calls to gettext have constant, double-quoted strings
as their arguments.  (Otherwise xgettext won't find the strings
for translation.)

Also, a few other gettext cleanups.

git-svn-id: svn://svn.code.sf.net/p/phpwiki/code/trunk@803 96ab9672-09ca-45d6-a79d-3d69d39ca109