Update Geoip module.

This patch provides the following changes:
* Updated Geoip library to the new Geoip2, which can be found here https://github.com/maxmind/libmaxminddb
  This lib has new API, supports a new database format, and is supposed to be more precise.
  Some related link: http://dev.maxmind.com/geoip/geoip2/whats-new-in-geoip2/
* Add support for City database which contains more informations. This is not shipped by default because of it's size (~20 Mo) but user can download it and it will load first if found by the module. 
* With this database, more natives are added which should cover most of datas (city, region, continent, timezone, latitude/longitude, distance). Also, some datas are now localized, and some natives can now retrieve a result in user's language if supported by database.
* A ```geoip``` command is provided mainly for debugging purposes. ```version``` which can output all metadada of loaded database and ```dump``` to retrieve all information of a given address IP in a JSON-like format.
* Project and pawn includes files have been updated.

Sorry for the messy patch, @TheDS! :P
You will notice probably some issue in first commits but I have fixed some after.
I know it's extremely unlikely, but you should probably add Antarctica for the sake of completeness. It looks like the code should be "AN" according to this: http://php.net/manual/en/function.geoip-continent-code-by-name.php