Testcases for test262 triggered bugs
Disable incorrect assert in numconv
Use def_prop instead of put_prop in JSON.parse()

With put_prop variant Duktape would incorrectly parse a JSON object
containing a '__proto__' named property.  Such a property must be
parsed as a plain property and must not affect the object's prototype
(ES6 inherited __proto__ property).
Improve misleading error message from duk cmdline
Document JSON reviver corner cases
Add JSON __proto__ reviver corner case test (now fails)

Add more testcases for parsing __proto__ in JSON.  The current implementation
fails when a reviver is really clever and deletes the own property '__proto__'
when called for another property (prior to __proto__).  This is very much a
corner case.
Release note update
Update test262 known issue list: one bug fixed
Merge branch 'test262-assert-fixes'
Ditz issue update