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.

Also don’t handle logger fds outside of Logger, and mark private
objects and methods.

Status and Command are now slotted classes instead of namedtuples,
which led to a few changes to access them with their named parameters
instead of as a tuple.

“short” being a C type, I renamed Command.short into
Command.short_desc, which is more explicit anyway.

I also renamed possible_show into POSSIBLE_SHOW, as it is a
module-level constant dict.

(it does both by default, and is better)

also, typo

The handlers are always there, but we only get carbons events when the
server sends them to us, which is only when we enabled them.

fix #3104

also fix a check that would make the handler never trigger…

(and restore it afterwards)
Could take care of some refresh issues with the position of the cursor

move the modulename to bookmark → boookmarks
add a bookmarklist class with
remove module-level variables
do a features check on startup before trying to fetch
    the bookmarks

and improve the message.

Exit almost gracefully instead of generating gigabytes of error logs.

TODO: pressure the python maintainers into dropping ncurses and curses
      support, and use ncursesw only instead.