Feature Proposal: Set a custom tiling ratio and offer gaps between tiled windows

Hello,

This is a patch over origin/master that implements two features:

a variable horizontal ratio width when tiling windows. initially, xfwm4 splits the screen into two columns that have the same width (50%). with "tile_ratio", you can configure a different width ratio. I set mine to tile_ratio=60 to have 60% for left windows and 40% for right ones. this variable sets the left part of the screen. The right part is calculated from the left value.
an empty gap between windows and screen borders to identify them better when tiled. "gaps_outer" sets gaps between windows and screen border. "gaps_inner" sets gaps between windows. I set mine to gaps_outer=10, gaps_inner=5. This means there is a 10px wide gap between windows and screen border and 10px (2*5) wide gaps between windows.

Attached are a patch and a demo screenshot.