Bump to version 0.3.0

- Changed the API for `Gradient::Map` to be invoked by using an array of `Gradient::Point` rather two arrays of `Gradient::ColorPoint` and `Gradient::OpacityPoint`
- Introduced `Gradient::PointMerger` to take on the previous responsibility of `Gradient::Map`

Author: zeevallin

lib/gradient/version.rb

@@ -1,3 +1,3 @@
 module Gradient
-  VERSION = "0.2.4"
+  VERSION = "0.3.0"
 end