Split SIP/InverseSIP into separate implementations.  Fix inverse sip to be a full polynomial, applied directly to the input.
Split SIP/InverseSIP into separate implementations.  Fix inverse sip to
be a full polynomial, applied directly to the input.

tbabej/astropy,astropy/astropy,lpsinger/astropy,stargaser/astropy,funbaker/astropy,kelle/astropy,funbaker/astropy,pllim/astropy,joergdietrich/astropy,larrybradley/astropy,bsipocz/astropy,stargaser/astropy,mhvk/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,kelle/astropy,StuartLittlefair/astropy,pllim/astropy,DougBurke/astropy,saimn/astropy,kelle/astropy,larrybradley/astropy,kelle/astropy,aleksandr-bakanov/astropy,mhvk/astropy,dhomeier/astropy,saimn/astropy,astropy/astropy,DougBurke/astropy,dhomeier/astropy,saimn/astropy,saimn/astropy,larrybradley/astropy,AustereCuriosity/astropy,mhvk/astropy,dhomeier/astropy,StuartLittlefair/astropy,lpsinger/astropy,tbabej/astropy,tbabej/astropy,astropy/astropy,lpsinger/astropy,joergdietrich/astropy,funbaker/astropy,MSeifert04/astropy,lpsinger/astropy,bsipocz/astropy,joergdietrich/astropy,mhvk/astropy,astropy/astropy,larrybradley/astropy,kelle/astropy,aleksandr-bakanov/astropy,tbabej/astropy,bsipocz/astropy,AustereCuriosity/astropy,DougBurke/astropy,DougBurke/astropy,larrybradley/astropy,StuartLittlefair/astropy,pllim/astropy,joergdietrich/astropy,StuartLittlefair/astropy,MSeifert04/astropy,AustereCuriosity/astropy,dhomeier/astropy,AustereCuriosity/astropy,funbaker/astropy,pllim/astropy,stargaser/astropy,MSeifert04/astropy,dhomeier/astropy,bsipocz/astropy,tbabej/astropy,joergdietrich/astropy,pllim/astropy,lpsinger/astropy,saimn/astropy,MSeifert04/astropy,stargaser/astropy,astropy/astropy,mhvk/astropy,AustereCuriosity/astropy,aleksandr-bakanov/astropy