SDF Metadata used in different shaders not read and stored in Font

[lusius]

Using an alternative SDF rendering technique that seems to work better for rendering small text in our case, needs additional metadata information from the fontfile.

Getting this data can be added in FontParser and stored as new variables in h2d.Font

Exampel code is found here:
https://github.com/Chlumsky/msdfgen

[lusius]

Adding code in a sec.

[lusius]

Related mr

#1230