Computing GFs for tide gauges, GPS buoys, OBPs, etc.

This is not nearly as streamlined as for the other data types and could you use some refactoring. Currently it's a 3 stage process

1 Produce displacement GFs and synthetics for a grid of seafloor points.

2 Assemble those GFs into GeoClaw dtopo files for the seafloor deformation associated with each subfault

3 Make a system call and run one GeoClaw simulation for each subfault.