Implement a filter that filters for Global IPs as per RFC 6890 - #7893

This PR changes the values of publicly declared constants, and while this may seem like no big deal for these particular constants, better avoid it unless absolutely necessary. Also, needs tests.

Thanks for looking into it - I added tests as per your request. As for the constant - in this case it seems cleaner and safer to update the constants, because otherwise they will either overlap with conflicting flags (e.g. FILTER_REQUIRE_ARRAY - which is not entirely obvious from the .h file) or will be largely out of order ( e.g. after 0x0800000 we'll have 0x40000000 which will be the only instance of that in the file ).

I actually updated the constant as it's better to have higher value than change existing ones. It's merged via d8fc05c

Thanks for the contribution of this feature!