Define alias ST_Perimeter (for geography ST_Length)
Okay this inconsistency I mentioned in #266 is irking me a bit. Can we PLEASE have an ST_Perimeter alias for geography tha tmaps to ST_Length. I know ST_Length returns the perimeter for a geography polygon but who is supposed to remember that?
Right now our geometry ST_Length returns 0 for polygon and people need to use ST_Perimeter. For geography you have to use ST_Length for both polygon and line strings. We could probably allow people to use ST_Length for geometry polygon if they want to as that is less of a breaking change than removing that feature in ST_Length geography.