More mathematical symbol icons

[melkstam]

Describe the requested icon
Explain the icon you'd like to see, and potential use-cases.

It would be nice to have symbols for some more of the common mathematical symbols.

Some examples are <, ≤, >, ≥, ≠, ≈, ∈, and ∉.

Screenshots

I think the characters are enough!

Additional context
N/A

[jakobskrym]

@melkstam looks like this is now coming 🚀

[jakobskrym]

@melkstam looks like this is now coming 🚀

[rektdeckard]

Added approximate-equals, empty, greater-than, greater-than-or-equal, intersection, union, less-than, less-than-or-equal, member-of, not-equals, not-member-of, subset-of, subset-proper-of, not-subset-of, superset-of, superset-proper-of, not-superset-of, text-subscript, text-superscript, tilde, vector-two, vector-three.