fix(math): update range mapper implementation

Description

Update range mapper implementation so that the scaling starts at the deadband edge (reduce discontinuities in standard output range)
Update range mapper implementation to fix bugs arising from comparing to T(0) when it should have instead been comparing against center_ or outputcenter
Update math example to have better range mapper test - and one which outputs csv for easier plotting / checking
Update range mapper docstrings to have more text and warning about input inversion

Motivation and Context

Previously the range mapper had some bugs depending on how the input or output distributions were configured (since parts of the code did a test against T(0) instead of center_ (input center) or output_center_). Additionally, the deadzone / deadband that was applied around center not only caused the output to be the output_center_ value, but also introduced a discontinuity in the output distribution for an input value of deadband +- center.

This PR fixes those issues and also adds a note about the possible deprecation / unwise use of the invert_input flag.

How has this been tested?

Building and running the math example on a qtpy esp32s3 and graphing the output of the range mapper test.

Screenshots (if appropriate, e.g. schematic, board, console logs, lab pictures):

CleanShot 2024-05-13 at 14 16 32 range_mapper.xlsx

range_mapper.csv

Types of changes

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[x] Documentation Update
[ ] Hardware (schematic, board, system design) change
[x] Software change

Checklist:

[x] My change requires a change to the documentation.
[x] I have added / updated the documentation related to this change via either README or WIKI

Software

[x] I have added tests to cover my changes.
[ ] I have updated the .github/workflows/build.yml file to add my new test to the automated cloud build github action.
[x] All new and existing tests passed.
[x] My code follows the code style of this project.

esp-cpp / espp