Ok there is a 1.0 tag with a -h option now:

alex@broken:~/Dropbox/projects/dirt$ ./dirt -h
Dirt - a software sampler, which listens for
OpenSoundControl messages on port 7771.
Mainly used with Tidal http://yaxu.org/tidal/
Released as free software under the terms of the
GNU Public License version 3.0 and later.
alex@broken:~/Dropbox/projects/dirt$ echo $?
0
alex@broken:~/Dropbox/projects/dirt$ 

cheers