Add RLIKE to Search Builder operators list

RLIKE is a very useful MySQL operator that allows regular expression matches on fields. One use case that came up recently was a request to search for contacts in ZIP code prefixes 940,941,942,943,944,949 (but not 945,946,947,948).

With the regular LIKE operator, this is a rather tedious Search Builder query with five "Also include..." clauses:
LIKE 940%
LIKE 941%
LIKE 942%
LIKE 943%
LIKE 944%
LIKE 949%

With RLIKE, we can use a single clause with a simple regex to match just the required prefixes:
RLIKE 94[012349]..

I'm sure there are many other use cases, and it's a simple change to CRM/Core/BAO/Mapping.php