Bug fixes and new features

New features:

• Support new positions for grid lines
• Introduced new axis architecture
• Added c3_chart_internal_fn.isTabVisible - #938
• Added Sass support - #837

Bug fixes:

• Fixed data.region dash line - #989
• Fixed convert json not to mutate input object - #993
• Fixed IE10 issue with getBoundingClientRect - #1057 #1003
• Fixed mouseout event to be skipped when chart is destroyed - #997
• Fixed legend item width when multiple charts rendered - #1011
• Fixed rotated tick text - #1012
• Fixed type handling in load api - #1013
• Fixed to avoid setting c3 class to body - #1014
• Fixed Function.prototype.bind polyfill #1043
• Fixed unexpected rendering failure on init - #975
• Fixed scrollbar when redraw - #1005 #1026
• Fixed axis.labels api
• Fixed tooltip position on right edge on Firefox
• Fixed data label for area chart
• Fixed error about event rect widt when no ticks
• Fixed flow
• Fixed to throw error when url not found - #960
• Fixed legend state when reverted
• Fixed tickInterval when transition
• Fixed label overwrap on left axis - #961
• Fixed legend overlap on Firefox - #1026 #1019
• Fixed region, text and grid when updated - #922
• Fixed undefined when axis.x.tick.count specified on category axis - #935
• Fixed draggable for multiple xs
• Fixed unexpected data binding on click - #915
• Fixed unexpected height when redraw - #942
• Fixed parseDate to handle string correctly - #943
• Fixed bar and event width - #945
• Fixed bindto to accept null and empty string
• Fixed empty pie chart - #952

Thank you for all of feedbacks and contributions :)