New 'grab_pointer' argument: 'resize_side'

The 'resize' argument is now called 'resize_corner'.
Reuse W
Unify tiled and floating pointer actions

The following 'grab_pointer' arguments are removed: 'move_tiled',
'resize_tiled'. The regular 'move' and 'resize_*' arguments shall be
used instead. The 'fence_grip' parameter is no longer meaningful and
has been removed. Moving and resizing now behaves the same for tiled and
floating windows.
Remove obsolete prototypes