Pirate sailing ships (with optional flags)

Pirate sailing ship models remixed from [OpenSCAD Pirate Ship](http://www.thingiverse.com/thing:12856), for use e.g. as boardgame pieces.

Features a bigger three-masted ship and a smaller two-masted ship. The models have been tuned so they should print nicely out of the box without supports.

Alternate versions of the ships feature a system of interchangeable flags; ships have a slot on the bridge deck that supports the included flags. Different colours and shapes of the flags can be used t