newRPL: Named subroutines proposal

[Helix]

Here is another suggestion to make code more readable.

In RPL, code like A B SIN * C + 'Z' STO is not very clear.
There is an elegant solution, provided that the flag -3 is set:
'Z=A*SIN(B)+C' DEFINE
(I must admit that I have discovered this possibility only today!)

It would be nice to have also the command LDEFINE, which would create a local variable, in the same way as LSTO. This would make newRPL more similar to modern languages, but still following the RPL syntax. Of course, there would be a cost in speed processing, but since newRPL is much faster than RPL, it could be interesting in most cases.