Picwriter

New features in this main release (available now on PyPi):
- Automatic hashing of components and automatic referencing (to prevent duplicate cells).
- Migration of all components to a new Component() class, rather than directly inheriting from gdspy.Cell classes.
- Euler bends now available for waveguide routing! Also, S-bends!
- Better handling of polygon points (number of points are automatically computed to make sure grid errors are below the threshold specified in the WaveguideTemplate)
- Multiple waveguide paths can be specified for routing at once (rather than just one clad path)

Library now includes critical building blocks for most common passive photonic integrated circuits:
- Strip, slot, sub-wavelength grating waveguides
- MMIs
- Directional couplers, broadband directional couplers, etc,
- Improvements to the spiral class
- and many more, now in the documentation

Also included now are functions for quickly performing mode calculations or FDTD calculations of sub-components using MEEP/MPB, the PICwriter cell, and a user-specified vertical material stack.

First release of the PICwriter library