Improve Volumio versioning

Currently releases are numbered as – and the second part is just a unique number that is incremented on every build for uniqueness (Meaning of numbers after dot ?)

Building upon Debian Bullseye is around the corner! - #3 by ashthespy, the current version numbers makes it rather tedious to figure out if bugs are from os/core/ui/plugins or some interaction b/w them.

I would suggest using some form of loose semver, but instead of <major>.<minor>.<patch>+<meta> something that makes more sense for Volumio.

Something that captures OS/kernel/package changes in one field - this changes quite rarely, so <minor> might be appropriate. Another field should capture information from the core/UI/plugins. Ideally all these components use semver already to keep compatibility b/w their complex linkage. So as previously, we can use a field that ties all this in to just an incremental number for <patch>

So we have something like <major>.<rootfs>.<vol>. Since semver supports metadata, you can still add alpha/beta/test information, build, or any more creativeness.

What Version Proposed
Test v2.907 2.907 2.1.907+alpha
Build failure 2.908 2.1.907+alpha+build2
Test Tidal plugin 2.909 2.1.907+alpha2
Test Qobuz plugin 2.910 2.1.907+alpha3
Test core, abc,xyz plugins 2.911 2.1.907+alpha4
Test UI changes 2.912 2.1.907+beta
Stable release 2.913 2.1.907
New mpd/shairport-sync 2.914 2.2.907
Change pi kernel 2.915 2.??.907
Change x86 kernel 2.916 2.??.907

The new build system makes it easy to build a rootfs once that can be tagged and reused. Rather than building everything from scratch and chasing some bug that comes from an updated xyz package…
But this makes it confusing – if you change say pi kernel, keeping everything else constant, it would be 2.2.907 that isn’t very intuitive if you are used to semver.

Additionally versions of core – ui - plugins should somehow correlate to <vol>. This should be possibe by using semver across the ecosystem, and the minor version is then set as vol.

# dev cycle towards release 2.907
core         :  2.<vol>.<patch>  --> 2.907.4
ui           :  2.<vol>.<patch>  --> 2.907.2
plug_tidal   :  2.<vol>.<patch>  --> 2.907.15
plug_qobuz   :  2.<vol>.<patch>  --> 2.907.2
plug_xyz     :  2.<vol>.<patch>  --> 2.907.1

This lets you iterate the plugins/core/ui during the testing:
2.1.907+alpha β†’ 2.1.907+beta β†’ 2.1.907.

Pro tip - collect and store this version info somewhere on the image, makes it easy to back trace what change is causing issues. Given Volumio uses nodejs and modules, it’s a no brainier to use semver and tag module releases using proper package.json for each component/module/plugin. This allows you to use npm and such tools that focus on dependency integration.