Implement ST_GeomFromTWKB

[strk]

As a companion to ST_AsTWKB, an ST_GeomFromTWKB would parse a TWKB bytea and generate a geometry.

[nicklas]

Support added in r13053 for the types point linestring polygon multipoint multilinestring multipolygon geometry collection

But not for the aggregate types in twkb.

If Debbie and Winnie is happy I think I close it in this state. Then the aggregate types will be for the future.

[nicklas]

Ok, I close this

[strk]

Thank you !