category names can contain a dash (-)

Exposing the bug with version 1.003:

    00:06 <@BooK> meta categories? phonetic
    00:06 <+meta> BooK: Categories for phonetic: de en fr it nl sw x-nato
    00:06 <@BooK> meta phonetic/x-nato
    00:06 <@BooK> allons donc
    00:08 <@BooK> mmm, joli bug
use PodSyntaxTests and PodCoverageTests dzil plugins
use the MetaTests dzil plugin
extra tests for the regexp filter

- test requesting more than can be returned
- test requesting items that do not exist
requesting a fixed number of non-existing items caused an infinite loop

if the first attempt returns nothing, that's because there's nothing to
return, so break out of the loop
document the /regexp/ parameter

move the explanation for count and /regexp/ out of the command
descriptions, since the behaviour is identical
small copyediting
Changes for version 1.004