Variables by these names are only used from the local wscript and when
running "waf configure", which already for other reasons only can run at
the top-level.
These variables are thus not mandatory and not used.
Terminology used by server and client was starting to diverge.
C++ classes ArdourStrips and ArdourGlobals classes have been
renamed to ArdourMixer and ArdourTransport respectively.
State node values for transport functionality have been simplified
and prefixed with 'transport_' to match what was done for strips.