Align items to the end

[jerone]

This is a WIP draft to align tool-bar items (button & spacer) to the end of the tool-bar. On the horizontal to the right, on the vertical to the bottom. Items can be aligned to the end by using a negative value of the priority property.

Tries to fix #93

Am not sure if this is the way to go or use addLeftTile & addRightTile like the status-bar package. Need to do some more thinking and testing.

Code used for testing:

    @toolBar.addButton
      icon: 'arrow-circle-o-right'
      callback: 'application:new-file'
      iconset: 'fa'
      priority: -50
    @toolBar.addButton
      icon: 'folder'
      callback: 'application:open-file'
      iconset: 'ion'
      priority: -51
    @toolBar.addSpacer
      priority: -52
    @toolBar.addButton
      icon: 'archive'
      callback: 'core:save'
      iconset: 'ion'
      priority: -53

[jerone]

I've been running this for a while now and it works great.

Anyone wanna give this a try /cc @suda @cakecatz

[cakecatz]

LGTM 👍