Add a test function to test Evoral::coverage() with all possible overlap
types. The first test (line 161) that expects OverlapExternal will fail
with the current implementation of coverage().
There's possibly still a discussion to be had about what the overlap type of
ranges with negative lengths should be: there are currently places in the main
Ardour code base where coverage() is called with ranges where start > end.
they are now done with region fades, rather than separate objects.
After this commit, Ardour will try to convert your session files
to the new crossfade format, but will make a backup in your
session folder first.
If you have works in progress using Ardour 3 it is
***STRONGLY RECOMMENDED*** that you back up session files before
updating to this commit.
git-svn-id: svn://localhost/ardour2/branches/3.0@11986 d708f5d6-7413-0410-9779-e7cbd77b26cf
