Allow strings as operator in rlm_python

Allow strings as operator in rlm_python

Because ('Tmp-String-0', '!*', 'ANY') is just so more readable than ('Tmp-String-0', 21, 'ANY'). Plain integers still work for backwards compatibility. As a bonus, we get rid of the OP table in radiusd.py: this module was not supposed to be included in scripts running from FreeRADIUS, but was still referenced from prepaid.py. As a bonus, we get rid of a table that was no longer in sync with the definitions in tokens.h.