shairport-sync: important bug fix and enhancements

[mikebrady]

Shairport Sync 2.6 brings an important bug fix and some enhancements:

1. A long-standing bug has been fixed which should make Shairport Sync more reliable and also compatible with Synology devices.
2. Shairport Sync now sets latencies automatically, like it always should have, making it easier to integrate with, for example, audio|acacia and Synology devices.
3. An extra setting allows you to use just part of the full level-control range of the mixer -- useful with the built-in DAC of the Raspberry Pi.

Signed-off-by: Mike Brady mikebrady@eircom.net

[mikebrady]

Thanks @Noltari!

[sbyx]

In general, please follow our guidelines, notably:

1. Add Signed-Off-By to your commit descriptions (not the PR) so they end up in the git history.
2. Prepend the commit-name with the packages they affect, so it is easier to distinguish which packages are affected by a commit.

[mikebrady]

Thanks for your comments, and apologies for not reading the contribution guidelines properly. Would my recent updates do the trick?

Regards
Mike

[Noltari]

Merged, thanks!