Adds a latency overlay to the built in Castbar that is included with Shadowed Unit Frames. This is only enabled for the player's cast bar.

Note:
For ease of implementation, this includes a local copy of the original casting bar code (taken from v3.2.11). Future updates to the unit frame mod may end up breaking this, and changes to the default cast bar (feature adds/bug fixes) WILL NOT be propagated if you use this addon. DO NOT go and bother Shadowed regarding cast bar bugs if you are running this.