init cesk-scheme-callcc from cesk-scheme
Preliminary call/cc support.

Sadly, quines diverge, because it is unsound now to assume the tight
connection between input and output in lists.
one call/cc example inspired by http://www.ccs.neu.edu/home/dorai/t-y-scheme/t-y-scheme-Z-H-15.html#node_chap_13 -- but shows limitations of just having call/cc without top-level
Merge pull request #6 from namin/master

call/cc