I required more information to be returned from a match other than
true/false in order to display also substitution information if
necessary, so MatchResult was born.  Only a single instance of
MatchResult is returned from FactsMapping.match, because MatchResult
accumulates results for any matching results.
Added additional checks to ensure fact statements cannot contain
variable expressions unless they are within a query statement context.
Made return types MatchResult as well to be able to return more than
"yes" or "no".  Added more complicated matching example where variable
matches an ArrayExpression.
Merge branch 'master' of https://github.com/nsharmon/jpro