Metsim

This just re-implements the PITRI methods to be significantly faster. Also fixes a bug on newer versions of Pandas that broke ascii input.

This is a small bugfix release that fixes the documentation on units of vapor pressure, as well as updating the unit conversions for vapor pressure to be correct.

Enchancements

- Allow for variable renaming in INI configuration files.
- Added capability for new YAML configuration file format
- Added capability simple unit conversions on output when
using the YAML configuration file format

Bug fixes

- Fixed a bug where `utc_offset` causes radiation to be
incorrectly scaled

This is a minor bugfix release that fixes 219