Changes to return value of pSA calculation script

Background

psuedo Spectral Accelerations (pSA) values are calculated in a cython script called rspectra.

It was found that the RotD values for pSA intensity measures were smaller than expected. Upon investigation it was determined that the spectral displacements were being returned instead of the pSA values.

This did not effect components such as the basic components and geom as they were calculated and returned separately.

Changes made

In order to get back the correct pSA values, the variable u was multiplied buy the square of the circular frequency (ω) before being returned. As the maximum pSA value for each period can be determined from this data, this return value has been removed from the script.

The maximum pSA values are now calculated outside of the rspectra script. Any future issues with pSA values should be reflected here.

Further changes in the same pull request include name changes to clarify that the RotD component can be taken of any intensity measure that takes an acceleration waveform as an input.

Verification

This change was tested using a copy of a Hossack broadband binary that was available to the tester.

Because the method of calculating the geom component was changed this is also included in the below table

While only one station is presented, this held true for all stations in the resulting intensity measure files.