Common code in ets_fiber_assigner and ets_shuffle

According to the current plans, both the ets_fiber_assigner and ets_shuffle components will share a lot of common functionality (e.g. reading/writing PFS designs/configs and accessing data bases), I plan to write several convenience functions that are used by both packages, and to improve maintainability I prefer not to duplicate this code.

Possible options are:

• the common code is put into ets_fiber_assigner, and ets_shuffle depends on ets_fiber_assigner
• the common code is put into ets_shuffle, and ets_fiber_assigner depends on ets_shuffle
• the common code goes into a new repository, and both packages depend on that

I'd prefer one of the first two options, since it avoids the bureaucracy necessary to introduce a new package, but I'd be happy to hear other opinions. mxhf , hassan ?