Bump version to 0.9.3.1.99 for development
Fix stat_summary examples that use geom_crossbar. Fixes #775
fix typo
Merge pull request #792 from crowding/patch-2

fix typo in geom_point docs
Fix for error when empty data and aesthetic are used. Fixes #587
Correctly load mgcv package whenever method='gam'
stat_bin: fix documentation for 'right' argument
Add facet headers to facet_grid