Add a list of servers to the Multiplayer tab

![serverlist-new](https://f.cloud.github.com/assets/1311964/70688/0a43af2c-5fbb-11e2-8cf8-d499927dd5c6.png)


The list will be downloaded from a server specified in minetest.conf via
serverlist_url = url
The default url is mesecons.net/server.list

There also is a local list (e.g. if server is down) in client/serverlist/filename, specify via
serverlist_file = filename
It saves your favorite servers, they will be appended when first connecting to them, your latest connections will be at the top of the list.

Serverlist file format:
[server]
name
address
port
description (whatever the owner wants to tell the player)

[server]
...

For an example list see mesecons.net/server.list

cURL is used for downloading the list. If USE_CURL is not set, it will load the local list only.