Pandorapsf

- Updated fits files on zenodo to include background area
- Updated the files stored on zenodo to use comressed images in astropy
- Added low resolution versions of the PSF to the package data to ensure that PSF models can be made offline. These files have no/small grids and do not include the background region. They are 1Mb each.

- Fixed sparse3d bug that broke ROISparse
- Fixed TraceScene to accept user defined wavelength grid
- Added TraceScene integrate_spectrum method
- Added documentation