Fixed getAttrs($cast) to getAttrs($cast=true) for several classes.
Fixed issue $this->getOptions for ImageUpload::render()
Fixed issue with unknown type attr for Textarea
Fix docblock class Control
Added Link element
Fixed default option label for class Control
Use getOptions for Link to set option 'container'.
Put space between buttons for Bootstrap/ImageUpload
Fix radio vs checkbox in InputGroup
Don't render attributes set to false or null.
Don't use camel casing in form id attribute