Metsim

This release includes a paper for submission to JOSS, as well as a new feature to allow for period-ending timestamps.

This is a duplicate release of what would have been 2.1.2, but due to messy git handling I am re-releasing it.

Enhancements:
- A new `--version` command line option to show the current version

Bug fixes:
- Now allows for CFTimeIndex as the time index for input data.

Enhancements
- Allow for specification of constant fields, through addition of an optional constant_vars section.
- Update version requirements to be less strict, and take advantage of new features

Bug fixes
- Fix for last time chunk when using `out_freq`
- Preserve dictionary ordering when using python 3.5 or earlier (fixes ascii read)

The newest release of MetSim provides an overhaul of the driver infrastructure which drastically decreases memory requirements for parallel runs as well as providing better parallel scaling, multi-node runs, and flexible domain decomposition via chunking.

Version 2.0.0 also implements UTC time offsets for large scale simulations and implements a new triangular precipitation disaggregation method. Various bugfixes and usability enhancements have also been implemented.