Adds recognition of the 'crunch' R5RS subset
Adds recognition of the 'crunch' R5RS subset

Crunch is a subset of R5RS that the crunch egg can heavily optimize via
c++ compilation. This change allows geiser to report to chicken
programmers whether the function is found within that subset, easing
development.

Details on the crunch egg can be found at:
http://wiki.call-cc.org/eggref/4/crunch

ChaosEternal/geiser