JSON.ArrayLength fails if 1st item is a string that begins with a question mark

[DanShockley]

The JSON.ArrayLength function wrongly returns zero when the 1st item in the array is a string that begins with a question mark.
However, the proposed fix for Issue #18 also fixes this bug.
Using JSONListKeys instead of JSONListValues also means the _keys (instead of _values) will never begin with a question mark for valid JSON.

Attached is a copy showing the problem, and a copy with the proposed fix.
JSONAdditions-ArrayLength-1st-item-begins-with-question-mark-bug-example.fmp12.zip
JSONAdditions-ArrayLength-1st-item-begins-with-question-mark-bug-FIXED.fmp12.zip