(pylint)

on_close wasn’t used correctly everywhere.
Also make the "close" commands for each tab specific to themselves,
rather than taking the current tab for closure.

fixes the circular import issue

All this crap is very brittle due to circular deps and python handling
them badly. This appears to be fixing some stuff, at the very least.

This is sed, so cleanup of imports (which can now be grouped together)
is not done yet.

On xmltab and listtab, the help text would be displayed in the input
after closing the tab.

And probably some other things that use ListTab.matching_names()

(keep a get_name() fallback just in case for now)

some stuff is now hidden wen the window size gets too small (might need
some adjustments). The info buffer in the roster tab, the userlist in
mucs, the vertical tab list, the info buffer everywhere, etc…

fixes whitespace issues, some builtin overrides, and some enormous lines

might make poezio run nanoseconds faster!

- avoid doing stringprep on every item, avoid at least one full copy
- add the number of items to the infowin

- No idea why subclasses of ConversationTab were working before
    (info_header was overriden with None in __init__)
- Or why the date parsing worked (“Exeception”)
- Some more reformatting with pylint indications
- Document each module in the tabs module

- todo: write a common import file to avoid duplicating the imports