Add support for JRiver Media Center

I would like you to consider adding support for jriver media center. JRiver is still under active development and the API rarely undergoes large changes which should ease the support burden.
JRiver is also among the last few media servers with a ten foot interface that supports Direct Show and Mad VR
Here is a link to a description from their homepage https://jriver.com/overview.html

Sorry but this is a really really too small market to be supported in Yatse.

With all the respect, I am not sure this is quite right. JRiver (the company) was founded in 1981 and managed to survive until today. Actually, they are expanding constantly to new platforms and the already big community keeps growing. JRiver Media Center (*2003) has become widely spread amongst audio (and home theatre) enthusiasts in the past, due to its superior feature set - incl. excellent support for DSP (and unencrypted Blu-Ray playback).

JRiver is even developing an ARM64 version, currently ‘beta’, which will run on my ‘Raspberry Pi 4 Model B, 8GB’ at a later stage - this opens up new possibilities!

I do understand, that there is no support for Volumio (yet ^^), as Kodi has become much better for music during the past few years. However, JRiver MC cannot be substituted by Kodi for several reasons at this stage - and probably not in near future. I, btw., am running Kodi and JRiver MC on differently prioritized systems.

Maybe one day, hopefully not too far away, we will be able to use JRiver MC with just one common remote control application - the great Yatse - instead of an additional “Gizmo” etc. :slightly_smiling_face: