support a flavor of _run+ (e.g. _run+?) to increment within unique sequence

[yarikoptic]

ATM _run+ would increment throughout all sequences, ie. for _acq-1_run+, _acq-2_run+, _acq-1_run+, _acq-2_run+ we would get _acq-1_run-1, _acq-2_run-2, _acq-1_run-3, _acq-2_run-4, whenever what we really want is _acq-1_run-1, _acq-2_run-1, _acq-1_run-2, _acq-2_run-2. So we should either fix "unconditionally" to do it within the name otherwise, or do it via some additional _run+?.

In general we advise against using such auto-increments since then becomes impossible to account for canceled runs.