Add option to specify new window type

[OndraM]

This extends creating new window added in #799, so that you can specify intended window type (tab or window), as defined in W3C WebDriver spec.
It seems more reasonable to have it as part of RemoteTargetLocator (not directly in RemoteWebDriver), similarly as Java bindings does. So lets move the method there and mark the previous one deprecated.

Example:

// before
$driver->newWindow();

// after:
$driver->switchTo()->newWindow();
// with window type specified:
$driver->switchTo()->newWindow(WebDriverTargetLocator::WINDOW_TYPE_WINDOW); // try to open new window
// or 
$driver->switchTo()->newWindow(WebDriverTargetLocator::WINDOW_TYPE_TAB); // try to open new tab

After merge:

• Update documentation
• Update changelog