Introduce Tag::renderTitle() and change Tag::getTitle()

[scrnjakovic]

I think we should consider changing implementation of Phalcon\Tag::getTitle in following manner:

public static function getTitle($prepend = true, $append = true) {}

public static function renderTitle() {}

So it allows following:

Tag::prependTitle('Hello');
Tag::setTitle('World');
Tag::appendTitle('from Phalcon');

echo Tag::getTitle(); // Hello World from Phalcon
echo Tag::getTitle(false); // World from Phalcon
echo Tag::getTitle(true, false); // Hello World
echo Tag::getTitle(false, false); // World

echo Tag::renderTitle(); // <title>Hello World From Phalcon</title>

This, obviously, breaks BC so I propose adding this for 4.0
I'm not sure on how to name Volt counterparts tbh.

Why do we need this? Well, it just makes working with titles and page titles far more convenient.

[niden]

This has been implemented in 4.x