Property definitions

gamnit $ BMFontAsset :: justify
	private fun justify(line_sprites: Array[Sprite], align: Float, line_width: Float)
	do
		var dx = -line_width*align
		for s in line_sprites do s.center.x += dx
		line_sprites.clear
	end
lib/gamnit/bmfont.nit:583,2--588,4