Re-enable some tests in test_igtools.py

Typo corrections in igtools.py:

Adjusting tolerance on ig test reference states. The states were nomi…

Super obvious bugfixes in a few files.

Merge remote-tracking branch 'origin/igtools-bugfixes' into igtools-b…

Update test workflow to run on all branch pushes.

Initial implementation of igtools testing

Tested Argon, adjusted density limits on propane

Transitioned all mp data to the new model, added R1234yf and propane;…

Started writing changelog entry, added todo list with sources, and ch…

Validated the new R1234yf data in the new mp1 model

Tested new CH4 and H2O mp1 data. Ready to complete transition to the …

Began drafting mp2 and started modifying mp1 for easier polynomial sp…

Initial implementation of igtools testing

Adding speed of sound referece in mp1 tests.

Fixing f&g calls in mp1

Add f&g calls to ig and mp1 test suites. Failing tests present.

Fix call error in test_es parameterization. Tests for ig classes shou…

Fix call error in test_es parameterization. Tests for ig classes shou…

Removed empty asIgtMix() and corrected __len__() bug

Pruned outdated doc files and updated copyright dates, built for 2.2.…

Updated the version number to 2.2.5

Corrected an additional error in the R1234ze saturation model

Corrected bug in IgtMix.mass(); still using abandoned _units attribute

Corrected bugs in _pref() and _argparse() with zero quantity and inco…