Support the clas12 experiment

For the moment the new experiment can be based from the work made for the bdx experiment.

In particular, the differences are:

• the timestamp of data is not synchronized with a GPS, but is rather synchronized with the run
• more may come during the tests or further development of the electronic boards. See possible updates in the comments below.

For what concerns the timestamp, the first issue to accommodate is that the run start time cannot rely on the localtime of the machine running the TSC.