Merge branch 'master' of github.com:johanmattssonm/birdfont

Merge branch 'master' of github.com:johanmattssonm/birdfont

Use other types of graphical objects

The previous version uses only simple paths this commit makes it possible to
add other objects like circles, rectangles and text. The refactoring
is the first part of the full SVG implementation.

White space fixes

Restructure lookups in gsub table
This commit does also change the order of subtables in the gsub table.
1. Chained substitutions
2. Context for chained substitutions
3. Regular ligatures

Add abstract table class