Gdspy

Version 1.4 of Gdspy introduces exciting new features to the library! And a completely revised [documentation](http://gdspy.readthedocs.io/).

The main additions are the classes [`FlexPath`](https://gdspy.readthedocs.io/en/stable/reference.html#flexpath) and [`RobustPath`](https://gdspy.readthedocs.io/en/stable/reference.html#robustpath) for more efficient path generation. They also support the original GDSII path specification for smaller file sizes.

There is also a new [`Curve`](https://gdspy.readthedocs.io/en/stable/reference.html#curve) class for SVG-like polygon creation and the introduction of Bézier curves and smooth (Metapost-like) paths.

When importing external GDSII libraries, those can now be loaded in binary form to avoid unnecessary parsing and polygon creation.

For a complete list of improvements, check out the README change log.

This is a minor release to fix building on Mac OS X Mojave.

Major improvements and features added! Check the change-log for details:

* `PolygonSet` becomes the base class for all polygons, in particular `Polygon` and `Rectangle`.
* Added `Cell.remove_polygons` and `Cell.remove_labels` functions to allow filtering a cell contents based, for example, on each element's layer.
* Added `PolygonSet.scale` utility method.
* Added `PolygonSet.get_bounding_box` utility method.
* Added argument `timestamp` to `Cell.to_gds`, `GdsLibrary.write_gds` and `GdsWriter`.
* Added `unit` and `precision` arguments to `GdsLibrary` initialization and removed from its `write_gds` method.
* Changed the meaning of argument `unit` in `GdsLibrary.read_gds`.
* Improved `slice` to avoid errors when slicing in multiple positions at once.
* Improved `PolygonSet.fracture` to reduce number of function calls.
* Removed incorrect absolute flags for magnification and rotation in `CellReference` and `CellArray`.
* Minor bug fixes.
* Documentation fixes.
* Removed deprecated classes and functions.

This release includes minor changes to ``GdsLibrary``.

The newest feature is the integration with [Appveyor](https://ci.appveyor.com/project/heitzmann/gdspy) to build pre-compiled wheels for Windows.

This release includes one major change that breaks backwards compatibility: addition of a `precision` parameter to `_chop`, `Polygon.fracture`, `Polygon.fillet`, `PolygonSet.fracture`, `PolygonSet.fillet`, and `slice`.

That is beacuse `_chop` is now performed in the C extension by the clipper library, which fixed a bug related to issue 23.

This release fixes a bug introduced in `fast_boolean` by updating the library to its latest version.

Gdspy license has also been changed to Boost Software License v1.0.

**Update (28/04/2017):** a precompiled binary for Python 3.4 has been added to the release (must be installed with `easy_install`). Thanks Jianhua Jiang for the contribution!