Add color functions

grey and alpha

framer/Color.coffee

@@ -153,16 +153,22 @@ class exports.Color extends BaseClass
 	toString: ->
 		return @toRgbString()
 
-	transparent: ->
+	alpha: (alpha = 1) ->
 		result = new Color
 			r: @r
 			g: @g
 			b: @b
-			a: 0
+			a: alpha
+
+	transparent: ->
+		@alpha(0)
 
 	mix: (colorB, fraction, limit = false, model) ->
 		return Color.mix(@, colorB, fraction, limit, model)
 
+	copy: ->
+		return new Color(@)
+
 	isEqual: (colorB) ->
 		return Color.equal(@, colorB)
 
@@ -254,6 +260,12 @@ class exports.Color extends BaseClass
 		c = -> parseInt(Math.random() * 255)
 		return new Color "rgba(#{c()}, #{c()}, #{c()}, #{alpha})"
 
+	@grey: (g = 0.5, alpha = 1) ->
+		g = parseInt(g * 255)
+		return new Color "rgba(#{g}, #{g}, #{g}, #{alpha})"
+
+	@gray: (args...) -> @grey(args...)
+
 	@toColor: (color) -> return new Color(color)
 	@validColorValue: (color) -> return color instanceof Color or color == null