Add request animation frame, is_point_in_path

This PR adds `Window#request_animation_frame` (with compatibility class) and `Canvas#is_point_in_path`.

Also the required version of opal was changed to support released versions. This is needed to be able to use released opal gem together with opal-browser from git in bundler. The dependency was set to be the same as it is now for opal-jquery (`['>= 0.5.0', '< 1.0.0']`).