FEAT: added implicit REDUCE to PRIN/PRINT argument.

Internally, it does an `reduce/into` in a static pre-allocated buffer, so that PRIN is more memory-friendly.
TESTS: change some older tests to adapt to PRIN/PRINT implicit reduce.
FIX: missing internal block buffer clearing for PRIN/PRINT.
FIX: minor code cleanup.
Merge pull request #436 from be-red/master

Markdown file added to curses
FEAT: added EMPTY? function.
FEAT: added CRLF definition.
FEAT: predefined Red word (avoid "invalid word" while DO-ing a Red script).
FEAT: multi-line input support for Red console.
Merge branch 'master' of github.com:dockimbel/Red
FIX: wrong argument type for EMPTY? function.
FIX: wrong code emitted for FOREACH's word argument compilation when word is locally bound.
FIX: lit-word! evaluation result not positioned right on stack for root expressions.
FIX: fixed bugs found in console, original code restored.
FIX: regression on SET compilation. Fixes words corruptions in GTK examples.
FEAT: added ?? debugging function.