Fix "ones" parsing as "1s." Require a word boundary between spelled numbers and units.
Fix "ones" parsing as "1s." Require a word boundary between spelled numbers and units.

This became very apparent with the addition of the word "a" to represent number 1. "11 AM" parsed as "11:00:00 PM 1m" which was very wrong. The words "a" "an" and traditional numbers "one" "two" etc. must now be standalone words in order to parse as numbers.

philiptzou/parsedatetime,cpatulea/parsedatetime,dellis23/parsedatetime,philiptzou/parsedatetime,bear/parsedatetime,cpatulea/parsedatetime,phoebebright/parsedatetime,kienpham2000/parsedatetime,idpaterson/parsedatetime,kienpham2000/parsedatetime,dellis23/parsedatetime