Fix typo
Fix multiple matching for dynamic groups.

Initial problem:
    Qtile proceeded matching rules until the end.
Example:
    When matching weechat in a first group and xterm in a second one,
    weechat will be setup into the second group.

New behaviour:
    Qtile stops matching after first result.
Example:
    Weechat matchs the first group and the matching process stops.

Closes #342
Merge branch 'develop' of git://github.com/qtile/qtile into develop
Allow to cycle in layout in both way.
Update because now Obj class is in the module pane, not bar.
Code update because Gap is in his own file (gap.py)
Class Gap, same as before but moved from bar.py to its own file.
Suppression of the Gap class (now in gap.py).
Simplification by inherit from the new global Pane class.
I let constants STRETCH, CALCULATED and STATIC defined in bar to not modify all other
files using them.
Simplification by inherit of the new global Pane class.
Code update to take account that now Gap is in its own module (gap).
Code update to take into account that Gap is now in its own module.
New class that allow the drawing of a window on the screen (a pane), window that
can contains widgets. 
No constrains are in this super class.
Known child class: Bar and NotifyWindow.
Obj class is now in this module.