Use the NamedPropertyHandler feature of v8 to wrap accesses to PHP properties
and methods from JavaScript. This enables us to support property
set/delete/query.
The `in` and `delete` operators in JavaScript work like the `isset()` and
`unset()` functions in PHP. In particular, a PHP property with a null
value will not be `in` the JavaScript object. (This holds when enumerating
all properties of an object as well.)
Because JavaScript has a single namespace for both properties and methods,
we allow the use of the `__call` method on a PHP object (even if the
PHP class does not natively define the `__call` magic function) in order
to unambiguously invoke a method. Similarly, you can prefix a property
name with `$` to unambiguously access the property. (When enumerating all
properties, properties are `$`-prefixed in order to ensure they are not
conflated with method names.)
The latest versions of v8 build libicu as well. If this isn't copied to
the lib directory, then the v8 version check fails (with a link error).
Ensure that this is caught at configuration time.
If you don't want to overwrite the system copy of v8 in /usr/lib/libv8.so,
you can use the --with-v8=<path> option to have php-v8js use its own
copy of libv8.
