- Add table and iter helpers. Move table.copy() to the table helpers.
- Store nodes in an array rather than a dictionary. Update my algorithms.
- Add Edge:getOption(), Edge:setOption() and Edge:mergeOptions().
- Add positioning helpers. Add table.count_pairs(). Update spring algo.
- Fix issues/breakage in the previous commit.
- Add spring and wetherelltree algorithms and the Vector class.
- Add missing copyrights.
- Update generation of TikZ code for edges a tiny bit.