Font embedding support.

[jbracker]

Adds the capabilities needed to embed fonts in SVGs.

• All font-face attributes are now supported. This is needed since other wise information may be missing when writing a font back to a file.
• The raw kerning information is saved in the font data to ease writing it back to a file.
• The new WriteFont module adds the function makeSvgFont to write a font (only containing a certain set of glyphs) back to SVG.
• The dependencies blaze-svg and blaze-markup are needed to create SVG output.