Remove AWT dependency

[SilverTiger]

Currently the font loading is done by using java.awt.Font. Since LWJGL provides some STB libraries it would be great to use STBTrueType and STBEasyFont, so that you don't need the JVM argument -Djava.awt.headless=true.

[SilverTiger]

Since the LWJGL 3.0.0-SNAPSHOT you can use NanoVG for rendering text. I will look into this before deciding which binding will be used in the Font class.