Cat Version 0.9

I've made a major update to the Cat manual and posted a new version of the Cat interpreter and source code which is now compatible with Mono (but so far only tested on Mono 1.13.8 under Windows XP). The type checker / type inference engine is now much more mature and well-tested.

The Cat interepreter and source code is all released entirely into the public domain.

Any comments, suggestions, or bug reports much appreciated!