Update music_timeline branch to latest changes

[fentras]

Updates https://github.com/vittorioromeo/SSVOpenHexagon/pull/346 and https://github.com/vittorioromeo/SSVOpenHexagon/issues/335.

This is an updated version of music_timeline branch that has been merged with develop branch (latest commit https://github.com/vittorioromeo/SSVOpenHexagon/commit/7f7d1665fd82dd92ead9c29109d2c3810271d601). I've also added an example level to showcase the new functions.

While building and reviewing the pull request I have made some observations:

• When building you will get __builtin_memcpy(__s1, __s2, __n) warnings but they don't break the build process.
• If you set a_evalTo or (a_evalToMs) to zero seconds it will work only at the start of the level and will not repeat once the music loops back at the start. Having a_evalToMs(10) makes it work sometimes but not every time. Having anything above a second will work every time. I assume it is related to the global timeline which manages to skip evaluation (a_evalTo and a_evalToMs) methods with times close to zero at the start.
• e_messageAdd* seems to have a random delay from zero to 20 milliseconds before showing the message but I assume it's just tied to the screen refresh rate.
• If you put a singe song in the pack it will be used for every level even if you explicitly state to use a different one in a level's .json, but that doesn't seem to be related to music_timeline branch.

In general this is a very nice addition and will help introduce more music-focused levels.

https://user-images.githubusercontent.com/26721650/196008984-b58e49f7-2876-41df-a39f-be8bbade1078.mp4

[fentras]

I completely forgot about https://github.com/vittorioromeo/SSVOpenHexagon/pull/346#issuecomment-852674353. Making it a draft for now.

[Bauumm]

actually wait, look: https://github.com/vittorioromeo/SSVOpenHexagon/pull/346/commits/6a30c61a21c3154259b3267ec7133a36fbddf373 tho im not sure if this is a good way to do it, since it'd imo make more sense to just have the segment be randomly selected based on the seed instead of saving the segment itself.

[fentras]

have the segment be randomly selected based on the seed

That seems like a good idea! I'll update it soon.