kgrid release 1.2

Mostly a maintenance update:

• Set minimum ASE version requirement and deprecation warning cleared (thanks @kavanase !)
• Drop support for Python 2.7, adopt Python 3.6 as the new minimum requirement
• Implement unit testing and Github actions

kgrid release 1.1

Fixed

• Python3 compatibility
• Bug in decimal place tolerance option

Added

• Comma-separated kgrid-series output option
• CASTEP-like reciprocal spacing cutoff option (2π factor smaller than KSPACING)

Changed

• Make filename a positional argument; -f or --filename no longer needed

kgrid version 1.0

This is a major version change and changes the structure of the project and the behaviour of the algorithm (for the better!)

Changed

• Correctly calculate reciprocal lattice vectors using whole
  cell. This is the new default behaviour. Former behaviour ("naive"
  apprach using only lengths of real-space cell) made available as
  option through Python interface and CLI.
• Restructure repository for packaging with setuptools
• Installation instructions in README

Added

• New emulation of VASP Auto and KSPACING modes.
• Setuptools installation
• New range generator for convergence testing: kgrid-series

kgrid version 0.2

Added

• Present useful Python API for use with Atomic Simulation Environment (ASE) calculators

Changed

• Import routine uses Atomic Simulation Environment. This adds a
  dependency, but permits import of almost any major crystal structure
  file format.