Document public interface of cfs_tpfa_residual module

This is Doxygen-style reference documentation only.
Merge branch 'master' into gravity-in-wells
Document public interface of compr_quant_general module

This is Doxygen-style reference documentation only.
Reformat to add Doxygen markup where appropriate
Document public interface of compr_source module.

This is Doxygen-style reference documentation only.
Rename CompletionData::gpot -> wdp .

This is in preparation of implementing actual gravity support in
(compressible) well-pressure solution.
Update documentation accompanying CompletionData structure.

Specifically, the 'wdp' member is a scalar value at each well
connection.  Phase behaviour is incorporated through other means.
Don't compare floating point numbers for equality.
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Merge branch 'master' into gravity-in-wells
Add constructor taking file name to GridManager.

Calls read_grid(). Grid fileformat not yet documented.
Added new tof computation utility.

This program assumes that grid, porosity, flux field and sources are
available to read from files. It does not compute any flux field itself.