Switch from unmaintained lash library to the more active ladish one

[GvMariani]

Building and running calf 0.90.3 on Rosa Linux (a Mandriva derivative) Fresh 2021.1 on x86_64.

The lash library, used for session management with jack sound server, is very old (last release in 2009) and unmaintained (no commit in the upstream git since July 2009). Luckily there is a viable replacement: the Nedko Arnaudov's LADI Session Handler (https://github.com/LADI/ladish). It's a complete rewrite of lash and is much more active (last git commit was in February 2021); it's already used by Carla and Cadence packages from Kxstudio project. It also sports an handy compatibility layer (liblash): all it should be needed to use it is changing the references to lash and its headers in those for the ladish compatibility layer and its headers.

The test patch attached simply does this, without bothering to change "lash" in "ladish" in the messages: it builds and runs OK for simple use on my system...
calf-0.90.3-use-ladish-instead-of-lash.txt

Please consider the switch...

[falkTX]

lash usage should just be removed at this point.

[GvMariani]

lash usage should just be removed at this point.
Oh, much better this way...
But the configure.ac on master HEAD still tests for it, so I guess this change is still in the future.