finnish vButton

[Gustav Hartvigsson]

vButton, an attempt at making a button for use in vProcessing needs to be finished.

A button returns true or false if a function is called on it, depending on if the button is clicked or not.
This is challenging due to that there must be a way of checking if the button is only clicked once per click, so that it does not continuously return true when hold down.

May be dependent on vRect and vText.