bus: fix parsing of matches against empty strings
bus: make sure exit-on-idle logic works on kdbus systems that do not generate NameLost
man: update sd_bus_request_name() man page
bus: properly parse NameOwnerChanged messages when caller explicitly wants to match against names coming/going
bus: fix make check
event: rework sd-event exit logic

With this change a failing event source handler will not cause the
entire event loop to fail. Instead, we just disable the specific event
source, log a message at debug level and go on.

This also introduces a new concept of "exit code" which can be stored in
the event loop and is returned by sd_event_loop(). We also rename "quit"
to "exit" everywhere else.

Altogether this should make things more robus and keep errors local
while still providing a way to return event loop errors in a clear way.
namespace: include boot id in private tmp directories

This way it is easy to only exclude directories from the current boot
from automatic clean up in /var/tmp.

Also, pick a longer name for the directories so that are globs in
tmp.conf can be simpler yet equally accurate.
git: update .gitignore
event: be more conservative when returning errors from event handler callbacks

We really should return errors from event handlers if we have a
continous problem and don't know any other solution.
event: when unreffing an event source from its own handler, detach fd from epoll

The pattern of unreffing an IO event source and then closing its fd is
frequently seen in even source callbacks. Previously this likely
resultet in us removing the fd from the epoll after it was closed which
is problematic, since while we were dispatching we always kept an extra
reference to event source objects because we might still need it later.