Step 1 - eliminate Split monoid and freeze
Merge branch 'master' into units
master -> units
initial measure work
Merge branch 'master' into units
enable merge
clean up
Global working
refactoring
simplify RNode
updated to work with new version of toOutput
changes to accomodate -lib and -core
Merge branch 'master' into units2

Conflicts:
	src/Diagrams/Backend/SVG.hs
	src/Graphics/Rendering/SVG.hs
updates to match changes in -core and -lib units

Notably, move renderTree out of Backend class
Dashing
fix warnings
Merge pull request #50 from diagrams/units2

Rework of units
change ts to rs to avoid shadowing ts from arrow
minor changes
use simple backend
better function names
Merge pull request #51 from diagrams/units-simple-backend

Updates to work with `Backend` redesign