Issue Releases, with Release notes, and a relatively easy ability to roll back

[aufdenkampe]

@SRGDamia1, this could be very handy for people using the Arduino IDE, and as a means to archive your carefully crafted zip file for older versions.

[SRGDamia1]

Feel free to make releases, though I'm not sure that it would make it any easier to update or roll-back anything in the Arduino IDE. I think you would still have to delete everything and re-create it. I guess I do that fairly frequently in PlatformIO by cleaning out my .libdeps folder, but it's a much safer clean-up because libraries are sorted per project instead of being set for everything.

The submodule_status.txt does list the current commit SHA for each submodule. I finally have Travis working properly to update all of the submodules along with the zip, so making sure the submodule links and are up-to-date is as simple as re-starting the most recent Travis job.

[SRGDamia1]

Part of the problem is that I just don't pay much attention to this repo. I nearly never use the Arduino IDE and use platformio.ini files for almost all of my library management. Since you are using that IDE, it would probably be best if you take care of the releases and updates.

[aufdenkampe]

@SRGDamia1, that all makes sense. I'll take over this effort, with a little help from you here and there! Thanks for all the work you've done so far!

[aufdenkampe]

There are useful notes in #7, and especially a great description from @SRGDamia1 on how the "carefully crafted -->->link<-<--" to the libraries.zip file is created, at #7 (comment)