Support POSIX-specified C-style escape sequences "\a" (alarm)
and "\v" (vertical tab) in command line arguments and regular
expressions, further to the support for them in strings added on
Apr 9, 1989. These now no longer match as literal "a" and "v"
characters (as they don't on gawk and mawk).
IOW, lex.c already supported these (lines 390-391 as of 4e343460);
the support needed to be added to b.c and tran.c.
Relevant POSIX reference:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html#tag_20_06_13_04
The lack of POSIX interval expressions[*] (a.k.a. bounds, a.k.a.
repetition expressions) in regular expressions is listed under BUGS
in 'awk.1'. Apple's version of onetrueawk has supported these since
at least 2009, judging by the date stamp on their src/b.c in:
https://opensource.apple.com/tarballs/awk/awk-24.tar.gz
A bug report prompted NetBSD to swiftly integrate this code into
their awk. This commit is based on that NetBSD diff.
http://gnats.netbsd.org/53885f3e4c4ca1d
b.c:
- Backport POSIX-standard interval expressions support in regular
expressions via NetBSD from Apple awk-24 (20070501).
main.c:
- Bump version ID.
FIXES:
- Add note and credit for this feature.
awk.1: section BUGS:
- Remove line saying interval expressions are not supported.
_________
[*] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04_06
