Add bullet.orient(top | bottom). Fixes #63.
d3.bullet: inherit transitions.
Link to vertical demo.
Update README.md
Add Airy’s minimum-error azimuthal projection.
Update README.md
Fix typo.
Add Chamberlin trimetric.
Add another Airy link.
Update README.md
Update README.md
Update README.md
Add inverse for d3.geo.interrupt.

This assumes non-overlapping bounding boxes for lobes.
Simplify slightly.
Add Gilbert’s Two-World Perspective.
Add tests for gilbert.
Update D3 dependency version.

Version 3.1.x is required as d3.geo.chamberlin uses d3.geo.rotation.
Simplify two-point equidistant.
Add link to Gilbert’s Two-World example.
Add thumbnail for gilbert.