Initial commit of the font writer for embedding fonts.
Further progress on font writing.
Added kerning support to the font writer.

For the to work, fonts now keep the raw kerning information.
Added font style to font data it was missing and is importent for embedding.

Also added default values according to SVG font spec.
font-weight is now saved as string since it is not actually a number according to spec.
Generalised reading strings from fonts.
Added support for font-variant and font-size in SVG fonts.
Added support for slope and accent-height in the font face.
Support for widths in font-face.
Support for all baseline attributes in the font face.
Support for overline and strikethrough attributes in font-face.
Merge pull request #9 from jbracker/font-embedding

Font embedding support.