Adding Filters

[chrusher]

I have added the filters of several upcoming surveys to FSPS (which work fine in Fortran programs) but I can't seem to figure out how to get python-fsps to build use my local sps_vars.f90 when installing so that it uses the correct number of filters.

[dfm]

In order to maintain compatibility, the Python bindings are currently hard coded to compile with the bundled version of FSPS. In the short term, you should be able to edit the version of FSPS at src/fsps/libfsps in a checked out version of this git repo, and then install that version. In the long run it might be worth adding a "use-at-your-own-risk" option to compile with an external version of FSPS.