add Jack Midi Input +many controllers

Nobody has claimed this yet.

Jack can use not only alsa and my alsa lmms-midi-config gets to dummy often, maybe because of changed alsa-device-#number or i'm not really sure why.
i don't know if it is really hard to implement, it works with alsa though
i'd suggest to add many midi-controllers not just one, so we could use few inputs for different instruments, for example midi-keyboard and midi-pad and midi-dj-mixer
really i'd like to use gamepad as beat controller with X-Y-Z as wheel for pitch or panning/volume/reso /octave shift etc just to have some fun with friends maybe .' ) - i think it's the same midi-input
for beat-bass editor assign controller and assign buttons to play one note of different instruments (beats&clicks) (can be also up-down-left-right) or few notes of one instrument (bass), mod-wheel can be assigned only for analog-sticks (distortion, amp, reverb and others)

the difference between keyboard and joystick is in channels - i think joysticks got only 1 channel and for midi there should be reserved address pools for 2-7 instruments so they wont reach more than 896 and the rest can work with joysticks, just tell user which pool this instrument is using

there's a lot of gamers in the world, i hope they'll be happy to be a part of music creation
and for me it is a better way to create not so automatic beat, doing it with midi-keyboard is not like with pads that i don't have, while i have gamepad and 2 joysticks with analog modulators - whole band

Start by surveying the existing ALSA MIDI input and controller-assignment paths; the issue does not name specific files, tests, or entry points. Compare the requested JACK input, multiple MIDI controllers, gamepad mapping, and channel or address pools with the current behavior. Done would require an agreed scope and implementation plan for the supported inputs and mappings.

Written by the indexing model from the issue text.