More abbreviations

[Enyium]

Question: What is "some": "sum" good for? Is this on the same level as "luv" for "love"? It's conflicting with "start of month": "som", though, and is also available using the command "phones some". Should this be removed?

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I took the abbreviated mathematical functions from:

• https://docs.python.org/3/library/functions.html
• https://docs.python.org/3/library/math.html
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math
• https://en.cppreference.com/w/cpp/numeric/math.html
• https://doc.rust-lang.org/std/primitive.f64.html
• https://doc.rust-lang.org/std/primitive.u32.html
• https://en.wikipedia.org/wiki/Trigonometric_functions#Notation

I added abbreviations like eq for "equals", or lt for "less than", because they can appear in function names.

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I deliberately didn't sort alphabetically in the third commit and grouped the new abbreviations. This should make review easier. After that: Should I ruthlessly sort everything alphabetically, even though this scatters month names etc.?