FIX: missing fix for COPY/PART on string! series.
FEAT: added internal `none/rs-push` function.
FEAT: add support for COPY, SET, TO, THRU, NOT, QUOTE, INTO commands in PARSE.
FEAT: significantly improved the composability of PARSE rules by changing rules stack usage.
FIX: many bugs revealed by PARSE unit tests.
TESTS: additional PARSE tests.