remove the get_isochrone subroutine that is not used and is broken by changes to the FSPS getspec call signature
remove the get_isochrone subroutine that is not used and is broken by changes to the FSPS getspec call signature

nell-byler/python-fsps,jrleja/python-fsps,bd-j/python-fsps,ajmendez/python-fsps,dfm/python-fsps