use the defaultWidthX, not the nominalWidthX
Merge pull request #56 from mapbox/defaultwidthx

Use the defaultWidthX as the starting value.

Previously, we used the nominalWidthX; however, this value should only be used when a width is specified in the charstring. Then the nominalWidthX is added to the glyph width. However, if no width is specified, we should use the defaultWidthX.
Expose the font's Top DICT.
Ignore generated files.
Unify Glyph interface.

Both TrueType and Cff glyphs now use the same class. In addition, both create a path that can be acessed using glyph.path, which gives the raw, unscaled path. This makes future performance improvements possible.
Merge branch 'master' into writing