Don't exit on BadDamage

If we receive a damage event, race conditions may have it that the damage
object is already destroyed by the time we try to access it.  Even so, the
default behavior of the X error handler is to exit, so we have to override this
behavior.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Grab input focus on startup

Input focus may already be held by a terminal emulator by the time we start up,
and the user won't be able to do anything.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>