Always use "var" in for loops.

This scopes the variable properly.
Fix resizing after resolution/strut change

Still not automatically triggered, but resizes correctly now.
Add shortcut to resize the master window (like xmonad)

This introduces the concept of a master to the layouts, though it's
currently pretty weak (just one, the only thing we do with it is this)
Update documentation
Merge branch 'resizekey'