Added GaussianBlurFilter and BilateralFilter to Mac

I've added the filters across to Mac (by removing highp, lowp, etc).

I've updated the filter showcase app, and it's lookin' fiiiiine.
![MAXIMUM VALUEZ](https://monosnap.com/image/DlhXpIrpuoMlnJrY4PRsEtmEF.png)
![mid-range](https://monosnap.com/image/ZshecdVfYb5nskFCC8e4e4V25.png)
![lo-fi](https://monosnap.com/image/CuDZI8FKBb3Y1ligFDhLpS27M.png)

:shipit: