Re: Contains and is contained by operators of inet datatypes

Review

- Applies and passes the test suite.

- I think this is a good change since it increases the consistency of 
the operators. I also like the choice of <<@ and @>> since they feel 
intuitive to me.

- I tested it and both old and new operators use the brin and gist indexes.

- The new spgist index does not support the old deprecated operators, 
which is intentional. I do not have a strong opinion here either way but 
some people may find this surprising.

- I am not convinced that your changes to the descriptions of the 
operators necessarily make things clearer. For example "is contained by 
and smaller network (subnet)" only mentions subnets and not IP-addresses.

- Maybe change "deprecated and will eventually be removed." to 
"deprecated and may be removed in a future release.". I prefer that 
latter wording but I am fine with either.

- Won't renaming the functions which implement risk breaking people's 
applications? While the new names are a bit nicer I am not sure it is 
worth doing.

- The changes to the code look generally good.

Andreas