[Mpi3-hybridpm] Endpoint proposal

[Snir, Marc]

I attached a new text of the proposal to the wiki.
main.3.pdf<https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/wiki/MPI3Hybrid/main.3.pdf>

<https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/wiki/MPI3Hybrid/main.3.pdf>Main changes:

Moved all non essential material to the end.
Shortened the introduction to explain clearly what motivates the proposal.
Changed the PGAS interface to reduce the number of distinct functions.

Marc Snir