Updates phpparser to version 3.0

[jaapio]

This is a BC break. We drop support for php5.

All tests are passing, but I'm sure that that doesn't say any thing. We will have to add tests to be sure everything works as expected.

[ashnazg]

I wonder... would an interim bump to 2.0 here give us a chance to solve the file-level docblock issue in phpDocumentor in the 2.x line?

[jaapio]

Php parser v2 requires php 5.4. That would either be a bc break

[max-voloshyn]

I would like to use @phpstan (in addition to this library) that requires "nikic/php-parser": "^3.0.2" so these changes are much appreciated 👍

[theofidry]

@max-voloshin you shouldn't install static analysis tools in your project root composer.json but either use a PHAR or install it in a separate composer.json which some plugins like bamarni/composer-bin-plugin helps you to do

[jaapio]

I'm closing this pr because we are moving forward with phpdocumentor v3 at the moment. There is no reason to support this old implementation of the reflection library anymore.