USB MIDI Class descriptors
Documentation update
Added basic class request processing
Merge branch 'develop' into usb-audio-midi

Conflicts:
src/global/defines.h
Merge branch 'develop' into usb-audio-midi

Conflicts:
	protoplasm.files
	src/global/defines.h
Added USB Interface Association Descriptor
Fixed default return value for usb_cdc_cmdcallback
Added USB MIDI configuration descriptor
Fixed USB descriptors
Fixed return code for usb_audio_cmdcallback
Added *.inl dependency for application object files
Fixed wTotalLength usage in descriptors
Loopback implementation for MIDI endpoint callback
Descriptor code formatting
Changed USB RX/TX FIFO sizes
Removed src/usbdevice/requests.md file
Updated Makefile.toolchain to use ARMTOOLS environment variable
Updated min/max macro definitions to specify result type
Documented XML_PARSER_BUFFERSIZE constant
Fixed documentation for AUDIO_FORMAT_TYPEI and AUDIO_FORMAT_TYPEIII