Issue 923 reformat electrolyte

[valentinsulzer]

Description

• Reformat electrolyte submodels
• Some optimizations to speed up tests

Fixes #923

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Merging #927 into develop will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #927      +/-   ##
===========================================
+ Coverage    98.05%   98.09%   +0.03%     
===========================================
  Files          226      221       -5     
  Lines        11164    11166       +2     
===========================================
+ Hits         10947    10953       +6     
+ Misses         217      213       -4     

Impacted Files	Coverage Δ
pybamm/expression_tree/functions.py	100.00% <ø> (ø)
...m/models/full_battery_models/base_battery_model.py	100.00% <ø> (ø)
...l_battery_models/lead_acid/base_lead_acid_model.py	100.00% <ø> (ø)
...dels/full_battery_models/lead_acid/higher_order.py	98.98% <ø> (ø)
pybamm/parameters/print_parameters.py	96.96% <ø> (ø)
pybamm/expression_tree/broadcasts.py	100.00% <100.00%> (ø)
...ybamm/expression_tree/operations/unpack_symbols.py	100.00% <100.00%> (ø)
pybamm/expression_tree/symbol.py	97.44% <100.00%> (+<0.01%)	⬆️
pybamm/expression_tree/unary_operators.py	96.35% <100.00%> (-0.53%)	⬇️
pybamm/models/base_model.py	98.57% <100.00%> (+0.01%)	⬆️
... and 37 more

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[Scottmar93]

Looks good @tinosulzer just one or two minor things. Definitely much cleaner and I like that you have changed the base_submodels methods in other submodels so that they accept the individual components instead of concatenations.

[rtimms]

looks good thanks @tinosulzer ! I'm happy once Scott is happy :)