You can use common without the others. Or should be able to anyway. It was to provide common features of logging, randomization, etc. for the test generator, miner, etc. Now that I deleted the miner it is waiting if anything else comes along.
The tester requires common. The visualizer requires the tester. That should be the dependencies.
Do you mean to put the version number also in the maven files? I am not sure how to best address that. The version in the build file has not been an issue so far as it has been the only one used to build the stuff. So I might have updated it for the next one or not, as long as it gets set with a correct version when a release is made that is all that has mattered.
Z+1 would be bug fixes, Y+1 would be some minor features, X+1 would be some bigger change in the usage pattern.
I don't generally use Maven so do you have some proposal for that? You could just leave the version number out and have it build whichever is there..
And yeah, the different parts have been versioned separately as something is added to each. Gives them a chance to live separately.