There's been no discussion on this, so I've picked one of the proposed
solutions and brought back MPI_COMM_GET_PARENT. The text should be
checked to make sure there are no problems.
I expect this to be the only nontrivial change in the dynamic chapter.
There will be lots of small binding changes, mostly to come into
conformance on the C++ side.
The function name changes, which will not be accompanied by
change bars (there are too many) are:
The last three are motivated by the nonexistence of a "nameserver"
class/handle. I personally like the cleaner scoping of the original
names, but consistency says otherwise.