Add missing CORE EXT words, probably get them all

[bshepherdson]

Currently missing:

• .R, HOLDS, and U.R
• 2>R, 2R> and 2R@
• C" and S\"
• CASE, ENDCASE, OF, ENDOF
• MARKER
• RESTORE-INPUT and SAVE-INPUT
• [COMPILE] (obsolete, maybe skip?)

[bshepherdson]

Got everything but S\" (difficult) and [COMPILE] (obsolete).