PHP requires boolean typehints to be written "bool" and disallows
"boolean" as an alias. This changes the error messages to match
the actual type name and avoids confusing messages like "must be
of type boolean, boolean given".

This a followup to ce1d69a1f6dcf15d43029301059c25e5bc09a577, which
implements the same change for integer->int.

We don't want ReflectionMethod::invoke() to simply ignore its first argument,
if the method to invoke is a static method. Instead we match its ZPP with
that of ReflectionMethod::invokeArgs(). Furthermore, we apply the DRY
principle by factoring out the code to a common helper function to prevent
inadvertent future divergence of the implementations of both methods.

As can be seen from the necessity to adapt some test cases, this causes a
BC break for some pathological cases. Therefore we apply this patch to PHP
7.1 only, which is still in beta phase.

Squashed commit of the following:

commit bdd3b6895c3ce3eacfcf7d4bf4feb8dfa61801fd
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Thu Jun 16 00:19:42 2016 +0300

    Fixed GOTO VM

commit 2f1d7c8b89ce821086d357cf65f629f040a85c03
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Jun 15 21:01:57 2016 +0300

    Removed unused variable

commit cf749c42b0b1919f70b1e7d6dcbfff76899506af
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Jun 15 19:06:16 2016 +0300

    Protection from $this reassign through mb_parse_str()

commit 59a9a6c83c66b666971e57f1173b33a422166efd
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Jun 15 18:14:50 2016 +0300

    Added type inference rule for FETCH_THIS opcode

commit 73f8d14a856f14a461430b3c7534ab2ce870cbf6
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Wed Jun 15 18:11:18 2016 +0300

    Restored PHP-7 behavior of isset($this->foo).
    It throws exception if not in object context.
    Removed useless opcode handlers.

commit fa0881381e8ae97e022ae5d1ec0851c952f33c82
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Tue May 31 12:25:47 2016 +0300

    Changed "Notice: Undefined variable: this" into "Exception: Using $this when not in object context".

commit e32cc528c0f2c97963d8ec83eff0269f1f45af18
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Tue May 24 02:02:43 2016 +0300

    Throw exception on attempt to re-assign $this through extract() and parse_str().

commit 41f1531b52113ec8a4c208aa6b9ef50f1386bb3f
Author: Dmitry Stogov <dmitry@zend.com>
Date:   Mon May 23 22:18:36 2016 +0300

    Fixed inconsistent $this behavior