pre-translate-po: handle more options

[rimrul]

I've only noticed this after #59 was merged, or I would've lumped them together as one PR

I'm not sure about the --glob=pattern and the various --foo=datestring messages that I caught. I think they should be <pattern> and <datestring> in the original docs. I'll probably amend this commit to exclude those and submit a patch to the mailing list.

[jnavila]

Please note that the ending colons will disappear once we use the latest version of po4a which correctly handles third level definition list items.

[rimrul]

That's the currently unreleased v0.64, though. Since po4a doesn't follow any fixed release schedule we don't have an ETA for that. And our regex treats the trailing colons as optional, so we should be fine with either version, shouldn't we?

[Beno1953]

not sure