Borderless and titleless for tile windows, patch included

Submitted by Pau Rodriguez-Estivill

Assigned to Olivier Fourdan @olivier

Created attachment 7492 Squashed commit proposal

I propose 2 more enhancements for the WM regarding tile windows:

If borderless_maximize is enabled it will also hide the window borders (just the ones next to the screen edge) of all the tile windows.
If titleless_maximize is enabled it will hide title bar, this is not very well supported by the theme files but the setting is only shown in tweaks, and visually looks good with most of the themes.

Also added the new checkbox (titleless_maximize) in xfwm4-tweaks-settings.

To see the patch in a separated commits take a look into: https://github.com/prodrigestivill/xfwm4/pull/1/commits

~~Patch 7492~~, "Squashed commit proposal":
borderless-tiles.patch