TestFunctionsForJSON: added new test methods
testFIELDFunctionWithInvalidIndexNotation &
testSET_FIELDFunctionWithInvalidIndexNotation; added a few tests to
testFIELDFunctionWithDotNotation & testFIELDFunctionWithIndexNotation,
for dot/index notation used on a primitive (or an array for the former,
or object for the latter); also, added useful (private) methods:
testProcWithValidJSON (2 versions) & testProcWithInvalidJSON; plus, new
procedure GetDocFromId, which is useful for debugging.