Corrected lower bound on diagrams-svg dependency to 0.8.0.2.

Previously specified version 0.7 lacks the 'svgDefinitions' field in SVGOptions.
Migrated to diagrams-lib-1.0.

Main change: coordinates are composed with '(^&)' instead of '(&)', which apparently has gotten incompatible with 'lenses'.
Merge pull request #1 from leftaroundabout/master

With diagrams-0.7, I couldn't get the project to compile, so I migrated it to 1.0. Might be a good idea anyway...