Cleanup handling of LFUN_LAYOUT_PARAGRAPH in getStatus

Cleanup handling of LFUN_LAYOUT_PARAGRAPH in getStatus

The way it works is:
* the inset defines allowParagraphCustomization() correctly
* Text::getStatus acts on it.

Note that, in Text::getStatus, testing for cur.inset().allowParagraphCustomization() does not make much sense, since one should pass the cursor idx as parameter. Actually, for some reason the safest bet is to use the owner of the Text object as inset.