QUDT Release 2.1.22

Release 2.1.22 includes:

• Refactoring of our community folder with an eye toward extensibility, driven by some of the contributions described below. Please see the community README here.
• Building on the above, @fkleedorfer has uploaded mappings from QUDT to IFC (Industry Foundation Classes) using SSSOM, as well as a variety of new quantity kinds and units relevant to the IFC world. You can find it all in the community/mappings/SSSOM/IFC folder.
• @paroga held our feet to the fire, so the distinctions between powers-of-2 prefixes (like Kibi, Mebi, etc.) and powers-of-10 prefixes (Kilo, Mega, etc.) is now cleaned up.
• Fixed some errors related to ForceMagnitude (thanks, @jpasini)
• Fixed a SPIN function definition filename for those who use SPIN (thanks, @mgberg)
• Fixed the symbol for the Siemens unit (thanks to @fennibay)
• Clarified the use of abstract quantity kinds, documented here (prompted by @mgberg)
• For those of you who use the SHACL schema, we have relaxed the constraint such that Units and QuantityKinds can have both a qudt:symbol (in Unicode) and a qudt:expression (in LaTeX) (@mgberg again!)
• Added ISO 4217 currency codes and currency numbers for all our currencies (thanks to @fkleedorfer again!)

A big thank-you to all of you for bringing many of these issues to our attention, and even better, for providing submissions to extend the size and capabilities of QUDT!