Prevent language shell commands from being used
with elua module's shell function.

For example, the following should not invoke
picolisp. It must simply return.

: (elua-shell 'picolisp)
-> "picolisp"
:
cpu module for picoLisp

Add preliminary support for the cpu module
for picoLisp. This include all functions
except for the ones pertaining to interrupts.

picoLisp doesn't support yet but soon.
Merge branch 'master' of https://github.com/simplemachines-italy/Alcor6L
Avoid fixing the size for local buffers.
Determine this with picoLisp's bufSize()
function.