Added calcApproxTextWidth util function. Fixed overlapping legend, as noted in issue #107.
Fixed issue #76.  Tooltips were not rendering for bullet charts.
For ticket AN-617. Added ability to create an 'average' horizontal line for cumulative line charts. Updated the example HTML file too.
Fixed issue #25. Updated logic in tooltip.js, so that tooltips are not inserted into SVG containers.
Merge branch 'master' of https://github.com/novus/nvd3 into development

Conflicts:
	nv.d3.min.js