Fixed coverage script not to refer to a different project...

and updated .gitignore to exclude total coverage stat file
Added weighted_round_robin util...

which is used for packing elements into a container (see pyamp's current
container implementation)
Added basic Fill element
Added a root element as the base point for a UI
Added Text element...

This necessistated making a utiltiy for padding lists sensibly too, and I
changed the interface for Fill slightly, given that it made sense for Text
to inherit from fill, seeing as Python's string alignment methods take a
fillchar. So, the char argument became fillchar to be less ambiguous.
Updated .gitignore to exclude vim temporary files
EDIT Made bad valign values more verbose...

and fixed import location of VAlign and HAlign in elements.py
Added ABCContainerElement and Stack element
Updated .gitignore for coverage data
Made bounding of element part of the ABC...

rather than doing it separately for each element. This should make things
more consistent, in that we will guaranteed that each element below us
does not exceed its alotted space.