Dwavebinarycsp

Fixes
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* 1-sat and 2-sat generators in the stitch function no longer use a deprecated dimod feature

Changes
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* Passes 2-sat generation to penaltymodel-lp rather than handling it in `stitch`

Changes
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* Drop support for Python 2.7 and 3.4

New Features
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* Uses the new `penaltymodel-lp` library for penalty models without auxiliary variables.

New Features
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* Make use of penaltymodel 0.16.x

New Features
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* Support for dimod 0.8.x

Bug Fixes
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* Fix case sensitive environment marker values in setup for windows

Changes:

- penalty model factory availability check deferred until import and first use (not during install; works with wheels)