Documentation fixes

Some of the links in the pypi version of the documentation were broken. I have added some code to setup.py to fix this.

Performance improvements and modernization

This release covers the following changes:

• Vectorisation of EFD calculation and inverse transform - contributed by @mgb45
• Support for the pyshp 2.x new file IO interface
• Support for pytest 5.3.5 and redesign of tests to cope with these breaking changes
• Updates to the CI pipeline
• Full testing of python 3.7 and 3.8 and dropping testing on python 2.x on Windows
• Highlighting the end of support for python 2.x
• Fixing typos in documentation

Import bugfix

Users reported that the module import failed on python3. This issue has been resolved in addition to some minor fixes to the documentation.

Python 3 support

The main change in this version is the addition of support for Python 3, and the preservation of functionality for Python 2 users.

Other changes are in moving the tests from nose to pytest, some minor refactoring, and the addition of windows CI via appveyor.

spatial-efd stable release

Implementing bugfixes and error handling and improving the documentation as part of the JOSS review process.

Production release for pypi

Stable version submitted to pypi