Disabled creation of SexpBool, SexpString, SexpDate

- There are too many classes to maintain.  We only need the array types,
going to remove non-Array types one by one
- removed SexpDate.  All dates are managed through SexpArrayDate now.
- Did some SexpArrayDate testing.  Need to do more
- Making an Sexp from a string or bool now invokes SexpArrayString and
SexpArrayBool