AWK & field-parser/record-reader routines shifted over to SREs.

SRE regexp system installed.

BEGIN process forms are now wrapped in a stdio->stdports call, so the
    body sees the I/O environment established by the pf's EPF.

New char-sets and predicates:
    printing blank control punctuation hex-digit ascii empty full
This gives full coverage of the Posix character classes
New char-set operations.
Space removed from char-set:graphic -- this was a bug wrt Posix definitions.
char-set-union and char-set-intersection now n-ary

Fixed bug with interrupt system that prevented sigalrm from being
caught by scsh programs.
    Mike Sperber & Kevin Esler

Dmitrii Pasechnik <D.Pasechnik@twi.tudelft.nl>
bug in delete code

reduce -> foldl (reduce-port, reduce-char-set)

FILE-MATCH still treats strings as Posix regexps; now accepts regexp args, too. 
