* Add driver for KY-040 rotary encoder
This driver has been taken from the Circle develop branch and can be
removed here, when the driver made it up into a circle-stdlib release.
* Add initial optional rotary encoder support
* Can change between voice and bank select mode by clicking the switch
* Turn the knob to select the voice or bank according to current mode
* Hold the switch for 3 seconds to reboot the system
* Program change from MIDI is only displayed in voice select mode
* Configuration for KY-040 added to CConfig and minidexed.ini
* Fix: m_I2CMaster has not been initialized in CKernel
* Make synth parameters configurable
* Add class CConfig, which holds the configuration
* Add template config file minidexed.ini
* Register panic handler in CKernel to allow to display assertions
* Fix: Performance timer did not show correct percent value with HDMI
* Add class CDexedAdapter
Some Dexed methods require to be guarded from being interrupted
by other Dexed calls. This is done in the class CDexedAdapter.
* Add class CUserInterface
The user interface should be implemented here. As a start it supports
showing the program number and name on the LCD display. The LCD output
is buffered, so that LCD writes from an IRQ handler are possible.
* Move MIDI handling from CMiniDexed to specific classes
* CMIDIDevice is the generic MIDI handler
* CMIDIKeyboard handles USB audio class MIDI devices
* CSerialMIDIDevice handles the serial MIDI device
* Now all MIDI inputs can work simultaneous
* Program change and bank select work with serial MIDI
* Add headers to all files
* Include voices.c in sysexfileloader.cpp
* Cleanup Makefile
* Support headless operation on Raspberry Pi 4
Some code cleanup for src/kernel.*
* Code cleanup for src/minidexed.*
Move implementation of constructors to minidexed.cpp
Reorder member variables
* Support multiple USB MIDI inputs at once
* Maximum 2 inputs on Raspberry Pi 1-3
* Maximum 4 inputs on Raspberry Pi 4
* Suppress frequent messages in MIDI dump
* Use minidexed.txt
* Document `SoundDevice` in `minidexed.ini`
Co-authored-by: probonopd <probonopd@users.noreply.github.com>