This reads a scheme initialization procedure from the resource
specified by the init-param with name "code" in the web.xml The
procedure is then evaluated and applied to this servlet.
A LocalVariable is denoted by its position in the environment, in terms
of the number of levels "up" we have to go (number of nested environments),
the number of variables "in" we have to go (ordinal position of variable),
and whether the variable is a "rest" (or "dotted") variable.
This class implements the three "hard" primitives in Scheme:
REPL.readStream(INPUT)
-- this returns a enumerator of all scheme terms in the
InputStream or Reader.