ggplot 0.5.4

	* border now drawn on top of geoms, instead of below - this results in better appearance when adjusting scale limits
	* ggplot() + aes() now modifies existing default aesthetic mapping, rather than overwriting
	* polish examples in facet_grid

ggplot 0.5.3

	* added experimental scatterplot matrix, see ?plotmatrix
	* added new border.colour and grid.minor.colour options for better control over plot apperance
	* updated theme_bw to do better when drawing a plot with white background 
	* better default colour choices for gradients (and more discussion in examples)
	* fixed bug in ScaleGradient2 where scales with different positive and negative ranges were not scaled correctly
	* allow expressions as result from strip.text
	* fixed rare bug in geom_vline and geom_hline
	* fixed example in geom_abline
	* tweaked display of multiline axis labels

ggplot 0.5.2

	* add argument to position dodge so it's now possible to accurately dodge things with different widths to their physical widths 
	* added median summary
	* new examples:
		* logistic regression example in stat_smooth
	* bugs fixed:
		* evaluation of arguments to layer is no longer delayed
		* can use categorical xseq with stat_smooth
		* x and y axes named incorrectly (thanks to Dieter Menne for spotting this)
		* can now pass position objects to qplot
		* y jitter calculated correctly, and jittered data rescales axis now
		* removed silly legend from quantile plot
		* extra arguments not being passed on to geoms/stats
		* fixed bug in stat_summary when summarising a factor
		* fixed bugs in stat_summary, geom_ribbon, and coord_trans examples

ggplot 0.5.1

	* renamed scale_manual to scale_identity to map position_identity and stat_identity
	* ensured all grob consistently named
	* renamed aesthetics argument to mapping to be consistent with description in book
	* added useful utilities for modifying grobs
	* bug fixes to x axis range with interval geoms
	* added ability to turn legend off for single scale (currently undocumented)
	* added economics data set and matching examples

ggplot2 0.5

 * complete rewrite of ggplot code base

 * id/grouping completely rewritten so that automatically grouped when any of the aesthetics is a categorical variable.  This behaviour is defined in the Grammar of Graphics, and makes things like qplot(wt, data=mtcars, geom="density", colour=factor(cyl)) work nicely
