More tests for Integers
Integer SkipUntil and TakeUntil
StringQuery.Map and MapWhere

Implemented Map and MapWhere on StringQuery, and made Substring and
Value derived operations from them. Further, reduced duplication across
all Queries by implementing all operations as derivatives of Where,
SkipWhile and TakeWhile.
All queries now have Map and MapWhere operations
IntegerQuery now has TakeBetween

TakeUntil, SkipUntil and TakeBetween are really a set. Will take these
to other queries once I"m happy with the semantics.
Merge branch 'TakeUntilSkipUntil'