fix: use height_cm instead of width_cm
New themes panel.margin.x and panel.margin.y

Fixes #839

Conflicts:
	NEWS
	R/facet-grid-.r

Resolved trivially.
Roxygenize
fix vertical justification for rotated text
Merge branch 'master' into feature/839-facet-margin-2
Merge branch 'master' into vjust
Merge branch 'master' into feature/839-facet-margin-2
Quick approximation for map projections

Instead of reprojecting everything, we just set the aspect ratio
of the plot to the ratio between the length of one degree of lat
over one degree of lon.
Add a new continuous colour/fill scale using colorbrewer colours

It fetches 6 colours from a colorbrewer palette and feeds them to gradientn. It gives very nice results even if the palettes were not intended for that use originally.
Add the American spelling synonym scale_color_brewerc()
Expand documentation of scale_brewer

As per Hadley's request: "add a few words to the main doc mentioning
that it does both continuous and discrete variables""
Further expand the description of scale_brewer

Give more precisions regarding the intent of the original colours and how
ggplot2 modifies them (in the continuous case).
Break lines at 80 characters
Change name from brewerc to distiller
Add examples for continuous brewer palettes
Updated documentation with latest version of roxygen
Fix bug in documentation

The latest version of roxygen figures out S3 methods on its own
Add parameter "varwidth" to geom_boxplot
Add initial stab at position_jitterdodge
Updates to position_jitterdodge()

  * Motivate the change in NEWS
  * Fix the style
  * Allow jitter.width, jitter.height, dodge.width as arguments
  * Improve the documentation