Previously, linking a field of e.g. a calc record to itself
(calc.INPA = calc.A) directly or through a chain of other records
that support to follow the link for attributes like units, precision
caused an infinite recursion and crashed the ioc.
Affected records: calc, calcout, seq, sub and aSub
Also added support for seq link 0 fields which had been added meanwhile.
Dirk Zimoch
7d73932dc8