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Major changes:
* Rearranged energetics. There are now three energetics classes:
* EnergeticsOld: this is the old energetics class (energetics_santalucia)
* EnergeticsBasic: this is an energetics class, based on energetics_daoe, which assumes that we know nothing about anything adjacent to the sequences. This likely makes the most sense for toeholds, or as a base for creating your own classes. It uses the new 'S' 'end' type, which is really just a sequence.
* EnergeticsDAOE: this is an improved version of energetics_daoe. It makes the most sense for sticky ends for DAO-E tiles.
* Added the multimodel module, which contains an endchooser that tries to optimize for multiple energetics classes at once.
* Added documentation!
Fixes:
* Fixed various installation issues in both Python 2 and Python 3.
* Removed auto-import of multimodel, which requires Python 3.
* Fixed examples in the README.