Add script to convert blackboard textures to dds + jpg

The text on the blackboards is all done by hand - purely out of academic
interest I'd love to take a crack at scripting it, but at the end of the
day it would probably look terrible, so I ended up doing these by hand
to maintain the aesthetic using my Intuos3 graphics tablet in Krita.
This script simply converts the .ora files exported from Krita to .dds
and .jpg files.

Hints for anyone repeating this in the future for another translation:
- If you can get my .ora files you can shortcut some of this since they
  already have the text erased and if the text is similarly sized you
  may be able to even use the glow layer. Naturally you still need to
  draw the translated text in.
- The game ships a blank blackboard texture that can be used to easily
  remove the text from the other blackboard textures - I did this part
  in the GIMP because I'm more familiar with that program. In
  whoisboters I left the "Boters rughhe?" text in from the original and
  erased the rest - later I added the question marks back via the magic
  selection tool to avoid copying the surrounding glow.
- In Krita 2.8, I used the pixel1 brush, setting the size to about 2.5
  for DidIkillthem and whoisboters, and about 3 for YouAreBeingWatched.
  Once I was happy with the shape of the letters I adjusted the spacing
  between them with lasso and move layer as needed.
- YouAreBeingWatched I duplicated the text layer and added a Gaussian
  blur (radius was 20ish I think) and reduced the opacity to about 15%
- DidIkillthem I used Texture_paint_chalk on a new layer, then applied
  a large amount of motion blur and reduced the opacity to about 50% -
  touching up some areas with the eraser where I had too much chalk.
- whoisboters I simply used the FX_glow_add brush to add glow where
  needed.
- From Krita, I exported the images as the standard .ora format which
  can then be read by The GIMP as an intermediate to convert to DDS via
  the gimp-dds plugin using this script for convenience. (GIMP can't
  read Krita's .kra format, though Krita *can* read GIMP's .xcf format -
  both can use .ora, making it a suitable format for interchange between
  the two programs).