Fix shairport issue, add mpd start/pause trigger

volmgt,ffstart,ffudevd changes

volmgt
- start all listed services with -F
- init mode (-i) to restart all services on all volumes
- fix locking
- don't remount volume if already mounted
fix ffstart
fix ffudevd logging

Add 6591 firmware 7.26.

Add AVM kernel 4.9.250, wireguard.
Fix unfs build.
Replace out of tree shairport-sync with buildroot version.
Some build chain adaptions.

Add 6591 firmware 7.26.

Add AVM kernel 4.9.250, wireguard.
Fix unfs build.
Replace out of tree shairport-sync with buildroot version.
Some build chain adaptions.

Squashed commit of 6591-devel

    Add -f to ffdaemon
    Provide wireguard for 7.21
    pihole fixes
    - Add to core image V28
    - libmultid: also change DHCPv6 port
    - pihole start/stop scripts
    - change pihole build
    Added socat, libmultid to base package
    Add -s to nvsync
    Add some sha files
    Switch 4.1.199 to avm kernel
    libmutdid: add missing ipv6
    Add dialog, ALSA doc
    Remove busybox from base image, add bb telnetd link in /usr/sbin
    S93-image: abort if already mounted
    buildroot with sdk build fix
    atom base tools rework
    System tools (ffinstall, ffstop, ffstart) enhanced
    ffservice: classify daemon failures as BAD, set return code for status
    Add ffshutdown/restart binaries
    Merge alsa branch
    ffdaemon: handle stale pid files when killing
    pihole: Run pihole-localhost service (LOCALHOST_UPDATE_INTERVAL option)
    shairport: change startup delay
    Makefile rework, separate toolchain build for 2020-02
    Refactoring
    - Binary ffwrap and infrastructure
    - Move fftools to common (ffwrap, ffdaemon)
    - usbplayd: Move in libmaru binaries, purge libmaru
    - Buildroot:
     - Start buildroot 2020-08
     - Split toolchain build

Squashed commit of 6591-devel

    Add -f to ffdaemon
    Provide wireguard for 7.21
    pihole fixes
    - Add to core image V28
    - libmultid: also change DHCPv6 port
    - pihole start/stop scripts
    - change pihole build
    Added socat, libmultid to base package
    Add -s to nvsync
    Add some sha files
    Switch 4.1.199 to avm kernel
    libmutdid: add missing ipv6
    Add dialog, ALSA doc
    Remove busybox from base image, add bb telnetd link in /usr/sbin
    S93-image: abort if already mounted
    buildroot with sdk build fix
    atom base tools rework
    System tools (ffinstall, ffstop, ffstart) enhanced
    ffservice: classify daemon failures as BAD, set return code for status
    Add ffshutdown/restart binaries
    Merge alsa branch
    ffdaemon: handle stale pid files when killing
    pihole: Run pihole-localhost service (LOCALHOST_UPDATE_INTERVAL option)
    shairport: change startup delay
    Makefile rework, separate toolchain build for 2020-02
    Refactoring
    - Binary ffwrap and infrastructure
    - Move fftools to common (ffwrap, ffdaemon)
    - usbplayd: Move in libmaru binaries, purge libmaru
    - Buildroot:
     - Start buildroot 2020-08
     - Split toolchain build

Add ARM toolchain.

Add missing ffstart.service

Support for Lab beta 7.19.

Fix nfsd startup script
Add Makefile option to enable console.
Fix LD_LIBRARY_PATH in ffwrap for application image
Add kernel kernel_4.9.175 for FOS 7.19.
Make options configurable in conf.mk.
uimg: verbose prefix is now optional.
Added package build template.
Prevent autostart of wireguard for FW > 7.12 (panic).
Giving ffimage=0 in kernel_args will prevent execution of application image.

Make use of /nvram (ext4 on eMMC) rather than using the encrypted fil…

…e in NAS storage.

buildroot image: Use ramdisk overlay for /var, not nvram.
nfsd: add "nfsd" service using unfsd.
uimg: Fix help message and update timestamp