Margins implementation on dimensions
Remove margin from ALL THE THINGS
fix for return value of margin
Merge branch 'master' into margins
Changed margin semantics to subtract from width rather than adding to it
Extended capabilities to directly set the element_width/height

* useful in the backend when no width is preset, to create the UI
  element with as much space as it needs and then set this as the
  width of the element
Use element_* in the backend for drawing purposes
Added a little dimensions class doc [ci skip]
Make moving elements take element_left/top into account

* Use element_left/top in backend drawing methods
* renmaed move in the backend to update_position, as we just want
  to update the position according to how the DSL position was
  updated - no need to pass params along
Removed a couple of unnecessary stubs and put in element_* in a few missing places
Adjusted comments on dimensions and extended them a bit
Merge pull request #467 from PragTob/margins

Margins implementation for Dimensions