updating ardour to 4.7

[Tobias Brodel]

hi there,

i thought i'd let you know that i've been working on a port of ardour 
version 4.7, you can find it here: 
https://github.com/tbrodel/freebsd-ports/tree/master/audio/ardour47

i've done some basic work in it over the last couple of months and 
everything seems to be stable.

ardour2 sessions are forwards-compatible, but once you save in later 
versions you can't go back. so upgrading will be tricky if people are 
dependent on ardour 2. for this reason some linux distros package both 
ardour2 and whatever is most recent.

i thought i'd ask if you've been working on an upgrade and whether you'd 
considered the upgrade/deprecation path question before i submit 
something to the bug tracker.

cheers,
t/