Dependencies

[zcaiElvis]

When installing SABer on Ubuntu 20.04 and Ubuntu 18.04, the following dependencies are missing:

1. libfreetype6-dev
2. libpng

[RyloByte]

I'll have to look into this a little more. I think I installed libpng-dev to fix mine, but I'll figure out exactly what is needed and add it to the install doc.