Add PCRE < 7 compatibility (Fixes bobthecow#25)

* Added tests against the (forthcoming) Official Mustache Spec. If yo…

…u're interested in running them, you've gotta update submodules: `git submodule update --init`

* Updated Mustache.php to pass all tests against the Official Mustache Spec, including:

    * Fixed issues rendering recursive partials and nested sections.
    * Fixed a horde of whitespace quirks.
    * Updated the `examples` tests to match the spec.

* This release *will* change whitspace output in most templates. The change is in the right direction, but consider this your warning :)

Fix a couple of quirks:

1. Double quotes are now escaped, per the mustache spec.
2. Associative arrays containing `null` values now work as expected (see http://hile.mn/8ZUs8m)

Mustache.php v0.3.0 changes variable precedence, which may break some…

… existing templates.

Class methods now take precedence over member variables of the same name. Given a Mustache class with a method `title()`, a member variable `$title`, and the template `{{title}}`, Mustache will now use the method instead of the member variable.

We also have 100% test code coverage. Sweet!

Update tag matching to allow newlines inside tags. This is consistent…

… with the Ruby implementation of mustache.

Completed implicit iterator pragma support.

* Fix object sections: Iterable (and Traversable) objects referenced …

…by section tags are properly treated as lists and iterated. All other objects are used for section context, but not iterated.

* Update tests for PHPUnit 3.5+
* Make 'examples' test script more robust, fix it for PHP 5.2.

Reset custom delimiters between successive calls to render()

PHPUnit config file and additional tests.

[temporarily] skipping delimiters test (until known issue with sectio…

…ns is resolved).

Multiple fixes, no API changes:

 * Fixed incorrect context inside partials. Partials now work with a view object of any class.
 * Fixed bugs with multiple invocations of render().
 * Fixed incorrect handling of whitespace around tag names.
 * Stopped passing context arrays around all crazy-like, now using context as a proper stack.