readme update
add some notes regarding debugging
_saveq renamed to >quotation after seeing it does the same

also deactivate new listener for now until clearer scanner/parser is in
place
rename parsing? -> parsing-word?, implement factor parser functions

accumulator vector is still on the stack, but otherwise parse-datum,
scan-datum, parse-until-step, parse-until along with execute work as
expected
clarify urrent compilation low-level functions