Plus42 algebraic expressions update

[Thomas Okken]

10:46 AM EST / 15:46 UTC -- Uploaded new builds

• STO → L(
• RCL → G(
• X⇄Y → (
• +/- → )
• Shift X⇄Y → [
• Shift +/- → ]
• Support for direct command mapping (skins with function names mapped directly to keys)
• Fixed a bug where the Windows version would create files with .f42 extension instead of .p42 when creating a new, empty state

I still have to add support for CATALOG, but apart from that, I think the equation editor is pretty much done.

Things I noticed and fixed after creating these builds:

• Direct command mapping: for 1/X, Y^X, and X^2, insert INV(, ^, and SQ(, not the RPN function names
• The : is pretty important so you shouldn't have to go into the ALPHA menu to type it; I put it on Shift ÷