ugly repl for Pika

Alright, [email protected]/eceval--devo--0.1 now has some code to
implement a REPL using Pika's FFI (very direct port of SICP's explicit
control evaluator), but (WARNING) the code is really ugly and it
doesn't work that well yet and there's very little error detection so
it's not suitable for anything but an example at the moment.

You can pipe some Scheme stuff from echo into eceval (and then
probably want to pipe that into head), but all that it handles
correctly right now are characters and booleans.  (I have the
framework code to eventually add bindings for the built-in routines,
but no actual code yet.)

Also, something as simple as (define foo #\c) seems to fail, so don't
expect much from this yet.  It also requires gcc to compile.  It's
package-framework compatible, so just download it into the src/
directory and reconfigure.

-jivera