Updated PHP-JS to use the new PHP-CPP extension API and made booleans…

… work correctly for PHP 7

Run foreground tasks on the isolate thread they should run on, cancel…

… tasks scheduled in the future when the isolate is destructed

Manually track external references, as v8 does not appear capable of …

…freeing externals in a timely manner - not even if you shutdown the entire v8 platform

Made the isolate used thread_local, which might fix intermittent crashes

renamed PxJavascript extension to PHP-JS

Work around issues in persistent handles to prevent v8 from tripping …

…over too many handles

Remove custom memory allocation routines: We'll stick with the 4.4.9.…

…1 of the v8 engine where this is not necessary since it appears to be much faster

Also allow returning the original ecmascript object from PHP