ST_SRID mutator function (sql/mm)

[strk]

According to iso sql/mm the ST_Srid function should work both as inspector and mutator. We should add the mutator (an additional arg).

[robe]

I don't like this idea at all. Works fine if you have a pure object model, but all our other functions that do set have ST_Set in them and I like it that way. Anyrate not something we should be pushing for 2.0.0 since there should be only one way of doing something this fundamental and introducing this alternative will just break a lot of apps and add another function.