[wp31s] simple equation editor ?

[Stephan2]

The intuitive usability should be a priority on the 31s, I really like it.
Here is a somewhat simplified proposal:

- simply use the existing registers instead of the proposed letter variables
- the equation above would then be
3 1/x
pi *
RCL0 x^2 *
RCL1 *
RCL2 -
[exit]
- the user provides values in the registers except for the one to solve for
- EQNSLV would then prompt for EQN# and R# to solve
- the solver then put its guesses into the register chosen and run the equation
- the result would be in X and the chosen register
- an equation editor could wait until a possible phase 2. Until then, there would
be useful preprogrammed routines provided in flash (TVM maybe?)

Necessary changes would be:
- new command EQNSLV in [more], prompts user for equation and register
- solver from 34s, modified to store guess in register (basically STO-> R#)
- ability to run command sequences from flash (no branches or looping necessary)
- no further new commands, changes to the front plate or anything else

I believe this could be an easy to use and powerful feature with many useful applications.