start dev work for v1.1
[#85] fix issue #85 by adding safe arc generation function
Merge branch 'gh-pages-dev' of github.com:NickQiZhu/dc.js into gh-pages-dev
improve unit test compatibility
making bar chart working with empty groups
[#90] improve bar/stackable chart's handling of empty groups
[#103] fix broken bubble chart selection
improve filtering robustness