added MultiBetween and StringMatch
Added IsArrInStr, cleaned up middlebox so it's now in the correct section (math, previously in tpa)
added filterpointsbox!
doc test(filterpointsbox)
added docs for the functions + added docs for some missing tpa functions.
Merge pull request #215 from Olly-/master

Added IsArrInStr, FilterPointsBox, MultiBetween, StringMatch.
Moved MiddleBox, InAbstractBox. Appropriate documentated added.