ISSUE-67 (string-less-than): need string predicates string-less-than, etc. [DTB]

ISSUE-67 (string-less-than): need string predicates string-less-than, etc. [DTB]

http://www.w3.org/2005/rules/wg/track/issues/

Raised by: Gary Hallmark
On product: DTB

in DTB, to compare 2 numbers N1 and N2:
numeric-less-than(N1 N2)
but 2 compare 2 strings S1 and S2:
numeric-less-than(compare(S1 S2) 0)

This is inconsistent.  We should use one or the other or both styles for all comparable datatypes: numeric, datetime, string