Read the glyph-metrics from the font files

Task Description

At the moment, we use a very slow process to get the basic font-metrics from the AWT. The long term plan is to use the font metrics of the font files directly, so that we can implement a linear-time text-size calculation. That one will be faster than the AWT, and will return more detailed metrics from the font (including what glyphs are supported by the font).

Solution Approach

Read the specs and start implementing it. There is no magic involved and all interfaces in LibFonts are already defined.