Consolidating similar units across systems

[yalinli2]

There are several similar units in different systems (e.g., IndustrialControlPanel, SystemControls), I'd like to consolidate them into fewer modules with some renaming for consistency and better organization, specifically

The following units will go into qsdsan/sanunits/_ion_exchange.py (see #55):

• IonExchangeNH3
• IonExchangeReclaimer
• IonExchangeNEWgenerator

The following units will go into qsdsan/sanunits/_controlling.py:

• IndustrialControlPanel (renamed to ControlBoxOP)
• SystemControls (this one is diff from others, maybe leave this out)
• SCGZyclonicControlBox
• RecyclingControls
• ControlSystem

The following units will go into qsdsan/sanunits/_hxs.py:

• OilHeatExchanger
• HydronicHeatExchanger
• DryerFromHHX (renamed to HHXdryer)

[yalinli2]

Other changes:

• ScrewPress in _sludge_thickening.py
• MURT (renamed from MURTToilet as the T stands for toilet) in _toilets.py (along with Toilet, PitLatrine, and UDDT)

[yalinli2]

Copying the notes on the differences between the various IX units from #65:

NEWgen & Reclaimer use zeolite (adsorbent, resin, a general term), have diff weights & regeneration freq.,

NEWgen & Reclaimer also have GAC, process is the same, just cost/materials

The type of acids can be different as well

See if it's better for 1 unit or different ones

[yalinli2]

As the many of the units (especially data) are specific to each system despite the similarity in their names, I think it'd better to consolidate the units for one system into one module, will do this when merging the gates branch into main