Improve unit consistency

[atomczak]

Some units are not consistent with others. I propose to reformat them, and add old notation to the mapping table.

For example:

• some multiplied with a dot, some without (Am²/Js - ampere square metre per joule second, instead of A·m²/(J·s), or ftlbs/sec).
• % m/md and dB(A) re 1 pW and Imp/kWh (kvarh) --> spaces in the unit
• % m/md;% m/md; --> no meaningful description
• (m²·K)/W vs --> bracket in numerator or not
• A/(m²·K²) vs --> same as above, but in denominator
• kg/cm/m² --> two slashes instead of bracket (expect kg/(cm·m²) - btw, what unit is that?!)
• ACH (air changes per hour) --> not consistent with others (expect AC/h)
• in/wc;inch of water;inH₂O --> isn't it still an inch?
• kW/(m³/s) --> isn't that kW·s/m³?
• missing slash or bracket: kW/kcfm;kilowatts per kilocubic feet per minute

[Baars-IT]

It's good, but pretty hard, to be consistent regarding units.
You can check if the unit is listed in the QUDT list (https://qudt.org/vocab/unit/). For example, A.m2/(J.s) is listed (QUDT name is A-M2-PER-J-SEC). They use dots and brackets in the "ucumCode".