PME-only counters are now reset with -maxh -resethway

Fixes #1125
For clarity gmx_pme_recv_q_x now returns and enum
and gmx_pme_send_switch is renamed to gmx_pme_send_switchgrid.

Change-Id: I21952780f0b719378d947a79324c844ccde7160a
Merge "PME-only counters are now reset with -maxh -resethway" into release-4-6