Upgrade Twig to 1.16.* from 1.15.*

Follow-up to #2172235: Upgrade Twig to 1.15.* from 1.12.*

Problem/Motivation

There has been some improvements to date handling, speed and error handling.

Change Log Diff:

1.16.2 (2014-10-17)
* fixed timezone on dates as strings
* fixed 2-words test names when a custom node class is not used
* fixed macros when using an argument named like a PHP super global (like GET or POST)
* fixed date_modify when working with DateTimeImmutable
* optimized for loops
* fixed multi-byte characters handling in the split filter
* fixed a regression in the in operator
* fixed a regression in the slice filter

1.16.1 (2014-10-10)
* improved error reporting in a sandboxed template
* fixed missing error file/line information under certain circumstances
* fixed wrong error line number in some error messages
* fixed the in operator to use strict comparisons
* sped up the slice filter
* fixed for mb function overload mb_substr acting different
* fixed the attribute() function when passing a variable for the arguments

1.16.0 (2014-07-05)
* changed url_encode to always encode according to RFC 3986
* fixed inheritance in a 'use'-hierarchy
* removed the __toString policy check when the sandbox is disabled
* fixed recursively calling blocks in templates with inheritance

* 1.15.1 (2014-02-13)
* fixed the conversion of the special '0000-00-00 00:00' date
* added an error message when trying to import an undefined block from a trait
* fixed a C extension crash when accessing defined but uninitialized property.

Proposed resolution

Update Twig to 1.16.* from 1.15.*

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A