Implemented Timings

This adds the /timings command based on the Spigot implementation, more powerful than the Bukkit implementation. It uses the same output format, so tools like the [Aikar.co parser](http://aikar.co/timings.php) can be used with its output.

Because this adds new API methods, the API version is now 1.1.0 (backwards-compatible).

Right now, plugins can be timed and vanilla/plugin commands. Further timings will be added in the next hours.

You can test using the [build 263 on jenkins](http://jenkins.pocketmine.net/job/PocketMine-MP/263/)

* [x] Plugin event timings
* [x] Command timings
* [ ] Entity timings
* [ ] Tile timings
* [ ] Chunk/world timings
* [ ] Other timings