Add type hints for scalar arguments and return values in Zend3

[danhunsaker]

Fixes #1656

[danhunsaker]

Discussion of the failed checks, and how to handle them properly, was started in #1656 before this WIP was submitted for reference.

[sergeyklay]

Could you adopt this to use in AppVeyor (Windows) too

[danhunsaker]

Hmm. fair point. I'll need to take a peek at the other test I pulled this block from and adjust it, too.

[danhunsaker]

This is addressed. Now handling the other issues that are preventing this WIP from becoming a true PR.

[danhunsaker]

OK, should be ready to go. The most recent change was to start using the PHP version to detect whether we have support for strict typing or not, and adjusting the expected exception accordingly. With declare(strict_types=1) in the files where strict type checks are appropriate, PHP throws TypeError before we see values passed to Zephir code. Otherwise, PHP coerces values to the expected type automatically, also before we see them. PHP 5.x doesn't support strict typing in any of its incarnations, nor does it support type hinting in the first place, so Zephir code will compile to the same C code as before, with ZE2.

[sergeyklay]

Thank you!