Start adding rectangle support to SFML module
Improve number support in ffi marshalling.

 * Marshall an integer correctly if a float or double is expected.
Fix command processing.

 * Wrap commands receieved over telnet in "^ [ ... ] value" so that
   the return value of the last expression can be captured.
Fix inclusion of SFML
Add keysAndValuesDo:
Enable debugging on darwin/scons
Make C code calling functions return an object
Begin fixing morphic
Fix stack description
Add json processor