When populating the list of recent sessions, and there's only one session
file in the session folder, don't assume that the base name of the session
file is the same as the name of the session directory.
Allows loading sessions that were created with trailing spaces in their
names from the recent sessions list, and also helps in the case that the
session file (or directory) was renamed.
There are actually two implementations of the 'recent sessions' chooser:
this applies to both. I suppose a useful project one of these days
would be to unify the two...
first-time user code remains in ArdourStartup
session selection/setup moved to SessionDialog
many other cleanups, logic improvements, and so forth to the overall session loading process.
Not 100% finished yet.