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.

Avoid surprises with some commands accepting quoted arguments and some other
not.

fix #2555

Make the "default" parameter optional and thus move it to the end of
the command with the other optional parameters.

And change all the calls.

also, check the features every rejoin for PrivateTabs
and refresh the window after displaying the features

no more stalling while waiting for a disco info while sending a message.

This reverts commit b46f0f5e.

Conflicts:
	src/tabs/muclisttab.py

Doing this made the unresized elements refresh in the old subwins,
causing glitches and weirdness. And anyway, the only problematic
element is the TextWin (rebuilding all the lines of a buffer is
expensive), but it already checks if the width changed.

(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…

(thanks eijebong)

config.get('option', 'value').lower() == 'value' is just ugly and
stupid, especially for bool.

One if in basetabs:556 was also missing a comparison, leading to True
whenever the option was set.

- 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