Point source SRF vs and density

[lispandfound]

Genslip v5.6.2 supports SRF 2.0, which outputs the Vs/Density to the SRF file which is useful for moment correction in EMOD3D, SW4. Unfortunately, the point source equivalent generic slip 2 srf does not support this. Update the point source code path to:

1. Continue to generate the point source SRF as we currently do and then,
2. Read the srf back and,
3. If the SRF version is 2.0 then,
4. Write the calculated Vs and density to the SRF file in the final location.

[lispandfound]

Beware of the units for Vs and rho in the slip file. I believe they are cm/s and g/cm^3 which necessitates scaling the Vs by 1e+5 before writing to disk.