fix: set hovered, active properly

[russmatney]

These were not implemented correctly. Works now as long as you set them
before creating the widgets in update(), something like:

local suit = require('suit')

function love.update()
	suit.setHovered("Button A")

	suit.Button("Button A", 5, 5, 100, 20)
	suit.Button("Button B", 5, 30, 100, 20)
end

function love.draw()
  suit.draw()
end

Related: #41