scatter-plot-for-main: add scatter-plot to main branch

[josmithiii]

Sometimes it is useful to plot two audio channels against each other in scatter-plot form (one as X and the other as Y).

[ffAudio]

Thank you so much for the contribution. I don't know if you saw it, but the windows compiler doesn't like the "not" keyword:
https://github.com/ffAudio/foleys_gui_magic/actions/runs/5749812977/job/15586106464#step:5:244

4>D:\a\foleys_gui_magic\foleys_gui_magic\modules\foleys_gui_magic\Visualisers/foleys_MagicAudioPlotSource.h(277,13): error C2065: 'not': undeclared identifier (compiling source file D:\a\foleys_gui_magic\foleys_gui_magic\Examples\SignalGenerator\Source\PluginProcessor.cpp) [D:\a\foleys_gui_magic\foleys_gui_magic\Builds\Examples\SignalGenerator\SignalGenerator.vcxproj]

I think it should compile if you change the not to a !

[josmithiii]

Thanks for letting me know about "not" on Windows. Hopefully I got them all.
I think I found where this happens under Actions, so I can catch these myself from now on (eventually),
but apparently I can presently only check back until the workflow has been approved.
It looks like the workflow can run on my fork, but I have to enable that:

"Workflows aren’t being run on this forked repository
Because this repository contained workflow files when it was forked, we have disabled them from running on this fork. Make sure you understand the configured workflows and their expected usage before enabling Actions on this repository."

I'll research what can go wrong, but if anyone knows that it's safe to proceed, please let me know.

[ffAudio]

Yeah, the next error is the and as well... cppreference says they are legit, and I found a microsoft page, which list those as well. But seems not standard. Compilers sigh
Unfortunately I have to click every workflow manually to run for external contributors, so apologies for any delay in advance...

[josmithiii]

Ok, I got the 'and' now. Incidentally, do you know how to convert the error message to a line number?

There is no hurry on this branch because it's going to be a draft while I polish it up (mostly to finish or take out unfinished stubs).
I thought the scatterplot was more standalone than it was, and didn't expect all my new plot stuff to get dragged in.
It seems like a good workflow to leave it in a draft feature branch until it's complete, and do my daily work in a merge of main with all of my feature branches. I have one or two more PRs to make, and then I'll be running on top of the latest. When a PR succeeds, I can simply delete that branch in my fork and stop merging it into my merge-branch.