Let users customize the word for each shortcut

[SinclaM]

A user on Discord has pointed out that the shortcut to, which produces →, conflicts with the function total. It is reasonable to want to use both of these in the same graph, but currently users would have to enable to via the control panel when needed and disable it when writing total. This is tedious and the same problem occurs with other shortcuts (e.g. between psi and epsilon).

It would be convenient if users could customize the shortcuts, so that, say, right would produce → instead of to. Implementing this would likely require modifying the internals of calculator_desktop-[hash].js, which would need to be handled with care so as not to conflict with DesModder.