Fix for the Read-more link in RSS/Atom feeds
Improvements to the file processor API:
- Processors can now bypass the "structured" processing imposed by PieCrust.
- Processors also get a chance do custom processing before/after the bake.
The LESS processor can now run the JS tool instead of using LessPHP.
Added Compass, Sass and YUI compressor processors to the built-in plugin.
These are modifed versions of the existing plugins.
Fixed unit tests.
Merged feed prepare fix.