Comments module: use CRC-16 as IP hash
Comments module: use CRC-16 as IP hash

Can't use CRC-32 because the result can overflow the column size when calculated using 64-bit PHP. Using CRC-16 ensures the result will always be within range in both 32- and 64-bit PHP installations. Fixes #159.

xenocrat/chyrp-lite,xenocrat/chyrp-lite