Rescale an SVG context before drawing, based on the origin offset
define a PlotGraphicsContext when saving as .bmp / .png / .jpg

no graphics context was defined in that case, causing an error. I'm using PlotGraphicsContext now.
added dpi kwarg
Merge branch 'master' into fix/svg-context-clipping
dpi kw
Merge pull request #149 from pthr/patch-1

define a PlotGraphicsContext when saving as .bmp / .png / .jpg
Merge pull request #111 from enthought/fix/svg-context-clipping

Fix SVG context clipping
Merge branch 'master' into release/440