Refactor entities

[noplanman]

• Complete rewrite of the Entities, making them more lightweight and almost code-free.
• Methods are now defined by DocBlock comments instead of actual code.
• Magic getters and setters are used for all Entities, including InlineQueryResult objects.
• Updated tests and example code.
• New namespaces for Keyboards and InlineQuery entities.
• New Keyboard and KeyboardButton creation, making it easier to create keyboards.

[noplanman]

I've just finished an initial version of the keyboard rewrites. Apart from supporting the keyboard object creation as it was till now, I've implemented a faster way of creating standard keyboards:

/**
 * Gives 2 rows, each with 1 button.
 *
 * [           Button 1           ]
 * [           Button 2           ]
 */
$keyboard = new Keyboard('Button 1', 'Button 2');

/**
 * Gives 1 row, with 2 buttons.
 *
 * [   Button 1   ][   Button 2   ]
 */
$keyboard = new Keyboard(['Button 1', 'Button 2']);

/**
 * Gives 2 rows, with 1 and 2 buttons.
 *
 * [           Button 1           ]
 * [   Button 2   ][   Button 3   ]
 */
$keyboard = new Keyboard('Button 1', ['Button 2', 'Button 3']);

// or...
$keyboard = (new Keyboard('Button 1'))
    ->addRow('Button 2', 'Button 3');

// or with an empty keyboard initialisation...
$keyboard = (new Keyboard([]))
    ->addRow('Button 1')
    ->addRow('Button 2', 'Button 3');

Here a few other ways to do the same thing with added properties:

$keyboard = new Keyboard(
    ['text' => 'Send Contact', 'request_contact' => true],
    ['text' => 'Send Location', 'request_location' => true]
);
$keyboard = new Keyboard(
    (new KeyboardButton('Send Contact'))->setRequestContact(true),
    (new KeyboardButton('Send Location'))->setRequestLocation(true)
);

Changing keyboard properties is easy:

$keyboard
    ->setResizeKeyboard(true)
    ->setOneTimeKeyboard(true)
    ->setSelective(false);

ForceReply and Hide keyboards are easier now too:

$keyboard = Keyboard::forceReply();
$keyboard = Keyboard::hide();

Note: These also return a Keyboard object, that can be manipulated the same way as any other keyboard.

Same system applies for InlineKeyboard.

This isn't 100% done yet and I need to refactor a bit and write the tests, but what do you think of this idea?

@akalongman @MBoretto @jacklul
Please give me your feedback 👍

[MBoretto]

Hello I would like to address this point:
all condition like:
$variable !== null

Need to be changed to:

isset($variable)

see for example User.php entity
then we also need to check carefully if all the updates are stored correctly in the database
You renamed the Unit dir in unit!
Amazing work!

[noplanman]

Conditions like $variable !== null make sense if we're checking for null only.
For other cases isset($variable) is ok, but should be used with caution.

Wherever I check for null it normally has it's reason, but I will double check!