Updated changelog with even more changes since 4.7.

CHANGELOG.txt

@@ -9,6 +9,9 @@
 - Added a YAML library (for developers!)
 - Block queues are now flushed based on attachment to other blocks
 - Sped up //fast mode by deferring lighting until after all blocks are in place. Has some bugs but it's at the very least good for previews.
+- Added l[eft], r[ight], b[ack] and f[orward] to the commands that take a direction.
+- Added a //g[en[erate]] command that can generate a shape given a formula
+- Added support for stretched cylinders
 
 4.7:
 - Added support for all the new items and blocks