Defining tracking_cloud and tracking_surfaced types. The arrays are
defined, allocated and filled with dummy values. Deallocation is
included at the end of DOUAR.f90.
No calculation is done with the tracking cloud yet.

deleting declared but unused variables, removing dummy arguments,
changing variables to double precision.
Not touching: uninitialized and more complicated warnings.

added variable calc_comp_velo, which is used to determined when compaction velocity should (or should not) be calculated

Added options for restarting with compaction output. Modified code to not read/write output for certain fields when they are not used (isostasy, compaction, nest)

DOUAR with cloud mat modifications from November/December 2012. Needs testing, may not work properly.

Added option of using previous steps strain rate to soften materials, updated only at the end of the previous step

Added output of yield_ratio and did minor cleanup; moved ziso stuff into bc_definition derived data type

Reverted to using 'include mpif.h' as the use of mpi.mod requires the MPI module be compiled with the same compiler as the DOUAR source, which is not true on geodyncomp