Textarea Editable Type

Added a textarea editable type, and updated the Text brick to use it.

STS (steps to test)
* Add a Text brick
* It should have a textarea input for it's "Text" attribute
* Type some text in there, line breaks should be preserved
* Save app
* Refresh
* Value should persist with line breaks intact

Fixes #1905 
`input` triggers while an input element is getting user modified, rather than at the end of their modification track. It might be more mobile friendly although I'm pretty sure mobile keyboards still send the `keyup` event.