Siepic-ebeam-pdk

- added a taper
- Monte Carlo

- Bragg grating
- Advanced Monte Carlo for waveguides
- Updated CML
- PDK Documentation on fabrication

- Windows compatible, namely Python 3 compatible.
- Improvements to INTERCONNECT integration.
- Two types of waveguides:
- ROUND_PATH: a single polygon. exports to INTERCONNECT as a single wavelength with a length
- Waveguide_Route: straight waveguide sections + bends, each with Pins. Exports as individual components, so you can include reflections and loss from the bends, and consider manufacturing non-uniformity.
- extra components, both GDS and compact model:
- broad-band directional coupler
- terminator
- PCells:
- ring resonator made up of two directional couplers
- Bragg grating (including compact model in INTERCONNECT)
- MZI layout scripted example - by Jaspreet

Additions:
- Verification output using KLayout's rdb & Marker Database Browser; easy to view errors in the KLayout tool

Improvements:
- multi-detector support for INTERCONNECT

Fixes:
- bug with verification; lists being over-written.

- Laser and detector PCells; user configures parameters
- netlist extraction
- Spice file generation
- call to Lumerical INTERCONNECT to simulate the Spice file; plot the results in a visualizer.

Updates:
- Python 3 / Windows compatibility: removed print ""; removed numpy
- menu item: delete extra top cells
- Correctly dealing with GUIDING_LAYER in ROUND_PATH waveguides, when user selects it
- waveguide length calculation added, including πr/4
- Spice netlist fixes -- tested that it works with Lumerical INTERCONNECT
- Added Lumerical INTERCONNECT launch to the menu
- waveguide - dialog for the radius
- floating point / rounding bug fixes
- Verification test GDS layout, to test/showcase capabilities.