Performance Improvements

[rkingsbury]

Summary

Miscellaneous changes to improve pyEQL's speed. Reduces the time required for many common operations by 3x - 10x.

Major changes:

• reduce calls to ureg.Quantity by using magnitudes where feasible
• use Quantity(float, 'unit') instead ofQuantity('float unit') which is substantially faster
• Instantiate and connect to the native database in pyEQL.__init__ to speed up subsequent access by Solution objects
• expand use of lru_cache for solution properties
• various minor optimizations

Results (results of %%timeit (ms), before / after)

1. Instantiate a 2 mol/L NaCl Solution: 301 / 84
2. s.get_activity_coefficient('Na+'): 27 / 14
3. s.conductivity: 143 / 44
4. s.ionic_strength: 5 / 0.5
5. `s.get_transport_number('Na+'): 2.4 / 0.5

[codecov[bot]]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Files	Coverage Δ
src/pyEQL/__init__.py	100.00% <100.00%> (ø)
src/pyEQL/engines.py	81.52% <100.00%> (ø)
src/pyEQL/utils.py	100.00% <100.00%> (ø)
src/pyEQL/equilibrium.py	50.00% <50.00%> (ø)
src/pyEQL/solution.py	83.12% <86.79%> (-0.28%)	:arrow_down:

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