feat: convert BACnet units to unit symbols (use SI where possible)

[kinnarr]

Fixes #3

Includes a script to check the conversation between BACnet units and unit symbols and also show missing units.

python helper_scripts/check_bacnet_units.py --all

[tilsche]

Generally it looks like it is all sane SI units plus Non-SI units accepted for use with the International System of Units. But I am not sure this will really help us towards our goal: Being able to simply slap on a SI-Unit prefix.

1. So many existing prefixes, so we need to parse them. But there is a lot of ambiguity, e.g. "dB" "min"
2. Parsing prefixes is even more error prone with squares
3. Adding prefixes with squares is error prone
4. Parsing and adding prefixes within ratios

At the end of the day, I think we need to find a library to actually achieve our goal (maybe this means in JS). And then we need to figure out if the library eats what the output of this.

[tilsche]

Unless that is picoHenry - the pH value is dimensionless.

[kinnarr]

So we need an empty unit here otherwise the BACnet unit name (pH) is used

[tilsche]

Not sure why you'd combine if / get. Could use get(unit_id, unit) or try / except KeyError

[tilsche]

dB is explicitly a non-SI with the following remark:

In using these units it is important that the nature of the quantity be specified, and that any
reference value used be specified. These units are not SI units, but they have been accepted by
the CIPM for use with the SI.

[tilsche]

That may even be "acceptable non-SI" but parsing hell...

[tilsche]

Suggested change

	217: "g /m³",
	217: "g/m³",

[tilsche]

The terms “parts per billion”, and “parts per trillion”, and their respective abbreviations “ppb”,
and “ppt”, are also used, but their meanings are language dependent. For this reason
the terms ppb and ppt are best avoided. (In English-speaking countries, a billion is
now generally taken to be 10^9 and a trillion to be 10^12; however, a billion may still
sometimes be interpreted as 10^12 and a trillion as 10^18. The abbreviation ppt is also
sometimes read as parts per thousand, adding further confusion.)

[tilsche]

... maybe ....

[kinnarr]

To make this clear, the list of units is defined by BACnet and every unit not in the map will use is unit name from BACnet

[kinnarr]

Currently we use the following units:

264
amperes
bars
cubicMeters
cubicMetersPerHour
degreesCelsius
gramsOfWaterPerKilogramDryAir
hertz
kilovoltAmperes
kilovoltAmperesReactive
kilovolts
kilowattHours
kilowatts
litersPerMinute
litersPerSecond
metersPerSecond
millimeters
minutes
noUnits
partsPerMillion
pascals
percent
percentRelativeHumidity
pH
voltAmperes
volts
watts

And yes, 264 and noUnits are valid BACnet units