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.
Fix some typos in the docs
CHANGELOG for 0.7
Have Slice proxy cmd_ calls to the fallback layout.

I use Slice to create a fixed with browser window with a Stack of (depending
on screen width) one or more stacks next to it. This changeset helps getting
shuffle and split commands to the Stack.

Closes #369