- replace with plusOp for reductions. The old use didn't necessarily work
well with compiler resolution in all cases.
Simplify to use plusOp (and removed the old version).
[Does not affect very much code...]
COMP: incorrect include ordering for GeometricFieldFunctions
- header was included after the template code
REGRESSION: combineAllGather mapped to incorrect method (81fa7d08ee)
STYLE: use UPstream::commWarn(...) setter method