Improve reliability of MIDI sync by making BPM constant

Add feature for the app, when connected via MIDI to a DAW, to focus on sync accuracy and not worry about tempo accuracy (because tempo would be assumed/preset). Background info: I noticed that how it currently works is more like live tracking. If the song sending MIDI information changes tempo, the soundbrenner app will try to adjust to the new tempo, and this causes extra pulses to come through and it gets jumpy and offbeat, even if eventuallly it falls back into place. When the tempo is constant throughout a song, it is much better BUT still jumpy and not perfectly reliable (as a metronome for an on stage musician, it needs to be nearly perfect). My use case is that there is a click track running to the rest of the band's ears, and that source is also outputting a MIDI clock to the soundbrenner app. I need to be perfectly in sync with that click track and I've already seen the connection work and be in sync, but throughout the song it gets on and off beat and gets a bunch of extra pulses at times. It would be great if this option could work with the setlists feature on the app, where you preset song names and BPM. While connected to MIDI, you could select a setlist item and the Pulse watch will go for sync accuracy using that bpm as the baseline. The app could use a rolling average of the MIDI signals coming in to make sure it's in sync. Related to suggestion <@#145%%post%%145> , but proposes a solution with more detail

Changed the title from "MIDI sync with predetermined constant BPM" to "App: Improve reliability of MIDI sync by making BPM constant"

A comment from our engineer: in his opinion the current implementation of our MIDI solution is not very good and quite hacky. So he thinks before we do any further hacks such as making it an option to make BPM constant, it would be preferrable to re-do and improve the MIDI implementation as it is and see if that solves the stability problems (this is why we advertise MIDI Support as still in Beta)