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

Fixed a few compaction problems: Deallocating certain osolve fields after compaction; Storing densityp=density in initialize_compaction; Several small bugs related to calculating the compaction velocity

DOES NOT COMPILE!!! This is the first attempt at a complete compaction implementation. Needs debugging/testing!