Fix a few small bugs, add benchmarks.
write some generic code to be able to inline small lists into instances

use it for ConsEnv, Call and LetCont
reorder
make tests a bit more robust about the cwd
make comparisons work for bignums
introduce a SchemeException for user-level error messages
get rid of some of the Samemacsleerzeichen
a bug in -
add some machinery for better prim error checking

expose can now take a list of types that the primitive expects, and
produces error messages if things don't match
Merge branch 'master' of github.com:samth/pycket

Conflicts:
	pycket/interpreter.py