v0.3.0

Changes:

• groupHeaderRenderer for FixedDataTableColumnGroup is now used for rendering group headers, as specified in documentation #151
• Improved performance of layout calculation that had been major part of JS time spent for every prop update 9936c5b
• Fixed rows positioning when using variable row heights #157
• Added prop to allow rendering of a lot of columns without huge performance drop by paging the columns like we do for rows, add allowCellsRecycling={true} to column config to enable this per column #49
• Changed cells to be rendered in absolute positions inside rows, to enable the above perf improvement.
• Stopped supporting React 0.12.0, we upgraded our React API usage, mainly getDOMNode to findDOMNode.