Hi folks,

Please see the attached patch that allows for post-processing of
PlantUML diagrams based on the exported file extension.  I currently use
this to transform text in PlantUML SVGs to paths with Inkscape so that
they can be embedded in PDFs with the text displaying at the correct
size in the image.  Since this post-processing occurs as part of the
export process it works perfectly with Babel's caching.  This ends up
saving me a bunch of time when making changes to only one of a
half-dozen figures.  The concept could also work as post-execute advice
on `org-babel-execute:plantuml', but I thought it would be more
accessible to users as a new customizable variable built into
`ob-plantuml.el'.

The only part I'm unsure about is that I use "%s" as the replacement
character when running commands over the exported file.  For example, my
"use Inkscape to pathify SVG text" command looks like:

    inkscape %s -T -l %s

I'm uncertain whether that's a non-recommended replacement character
but, either way, it functions well enough.

Please let me know if the patch is attached incorrectly: I tried
git-send-email but think I screwed it up somewhere as the previous
emails never appeared on the list.

Thanks for your time,
Nick