[#84] fix brush rounding issue when bar is centered
[#96] fix issue #96 in single selection chart
fix #98 on bar chart ranged selection
Merge branch 'gh-pages-dev' of github.com:NickQiZhu/dc.js into gh-pages-dev

Conflicts:
	js/dc.js
[#108] only draw bars within x domain
[#108] implement simple clipping for line chart
[#108] complete clipping implementation for composite chart
fine tuned bar title setting performance
Merge branch 'gh-pages-dev' of github.com:NickQiZhu/dc.js into gh-pages-dev