https://mojang.com/2014/04/minecraft-snapshot-14w17a/
It’s been a while since the last snapshot, hope you didn’t miss us too
much. We’ve been working a whole bunch on lots of internal rewriting (for
plugin API, to make things easier for ourselves and to make things run so
much more smoothly) but a lot of that isn’t in this version as it’s fairly
unstable.
Notable changes:
New highly customisable terrain generation! (Create new world -> “World
Type: Customized”)
New customisable world borders! Check out the /worldborder command.
Lots of bug fixes, performance gains and code cleaninguperizing.
???
Please report any and all bugs you find in Minecraft to bugs.mojang.com. If
nobody reports a bug, we can’t fix it!
// The Minecraft and Minecraft Realms teams