Blender Git Loki

blend file thumbnailing
- uses same thumbnail system as image browser
- blend files show thumbnails in ubuntu/gnome (freedesktop spec)
- 128x128 images are embedded into the blend file header, a simple loader avoids reading the entire blend file to extract it when generating thumbnails in the file selector.
When the image browser reads a directory it loads images and creates thumbnails, blend files embedded images are treated just like loading an image.
- the thumbnail is created from the camera view in solid mode. (no camera == no thumbnal).
- readfile/writefile.c: had to use the 'TEST' code name to save thumbnails, anything else would segfault older blender versions on load. (its not used elsewhere).