Move graph lag compensation to _graph.push method.
Include a lag limit to avoid issues following suspend.
Remove the lag, and make the lag_cycles visible to update_graph,
just in case we decide to make use of it.
Multiple inserts should not take too many cycles, thanks tych0.
Don't crash on exceptions from hooks
this_screen_border other_screen_border and urgent_border defined twice
Also remove duplicate urgent_alert_method

Thanks @WnP for pointing this out.
Fix typo in docs
Don't crash on moving to a nonexistent group

Fixes #360
Remove unused (and confusing) arguments
Log full exception from cmd_function() crashes
divide only if total isn't 0 in cpugraph

Closes #367
ellipsize text in tasklist widget

Closes #366
Fixes problems with focus when clicking windows

Conflicts:
	libqtile/manager.py

Closes #365

@tych0: small change to remove cmd_dummy and just use a noop function.