chore(grapth) Remove isTimeScale attr and related function.
feat(graph) Add domain api.
chore(graph) Clean up dataIds code.
chore(data.selection) Add length fn.
test(data.selection) Add tests for length().
chore(graph) Remove domain setter.
chore(test) Add graph domain tests.
Merge pull request #118 from racker/graph-domain-cleanup

Graph domain cleanup