boxes, phase 3
boxes working
diagrams using Tikz/LP: sketch
tikz engine implementation, first draft
tikz/lp engine basically working
 (some scaling problem remains.)
tikz/lp engine done
better names
add more layout combinators
tikz rendering of derivation trees: first draft
fixes
derivation trees: support delays
... and small other improvements
ensure no overlap of subtrees
try to center delayed hyps
interface on top of tikz paths
Merge remote-tracking branch 'origin/boxes'

Conflicts:
	MarXup/Tex.hs