Bugfix: Typo in i3.xsession.desktop TryExec rule.

Typo in executable for TryExec prevents LightDM from starting i3.
Include sys/sysctl.h after i3.h to prevent redefinition warnings caused by queue.h on OS X.
Bugfix: fix crash when using multiple for_window statements that move windows (Thanks Antonio)

fixes #1257
Bugfix: Set input focus with last timestamp

Setting input focus with the last event timestamp prevents race
conditions when setting focus.

fixes #1127