Creating a temporary branch for merging the 2011 developments from NOC and UKMO

When running an ORCA2_LIM3 reference configuration on an SGI-ALITIX-ICE system the job can fail with a claim to have exceeded the maximum permitted number of MPI_GROUPS. Raising the MPI_GROUP_MAX environmental parameter only delays this happening. The problem can be traced to the mpp_ini_ice routine which creates groups every call but never frees them. Possibly not a problem on all systems but the groups should be free'd after they've been used to create the new communicator (which is itself eventually free'd in limthd). The required changes will be made in lib_mpp.F90 on the trunk.