Fix graphics glitch in Blurry Halo Selection

This updates Blurry Halo Selection widget to the version found in zk repo to incorporate my fix at ZeroK-RTS/Zero-K#307.

Doesn't include color changes from zk because I'm not sure they will work in evo.

## Screenshot of the glitch

![bug illustration](http://i.imgur.com/1Ok4NEu.png)