Cleanups and addition of multiple "center" positions

[wdoekes]

Hi! Thanks for this extension.

On my very-widescreen monitor, I've been using the Unity multiple positions to position windows Left, Center and Right (all full height). With your plugin, I couldn't focus the center window.

I hacked it in there, and while I was at it, I tweaked some other oddities. The code could surely use some love, but this may be a start. If I'm not mistaken, the code is backwards compatible (apart from the removal of REVERSE_MOVE_CENTER, which now uses the more appropriately named MOVE_CENTER_ONLY_TOGGLE).

When testing the positions, I've pressed various combinations on the numpad and observed the window-move behaviour. It generally behaves as expected, but sometimes the window refused to move or had an unexpected width or height. I suspect that may be caused by the gratuit use of -1 (maximized X and Y position) in the plugin. As far as I can tell, the behaviour is better than it was. But this could also use some extra love.

[negesti]

very nice. i will check an merge this on the weekend

[negesti]

sry, took a bit longer then expected to check this

[wdoekes]

No worries. I can be a lot slower :grimacing:

Thanks!