Use "we-" prefix for commands
Clean up serialization

  * Adds a header to serialized data (to make version checking sane).
  * Removes the duplicate deserialization for `worldedit.deserialize` and `worldedit.allocate`.
  * Optimizes `worldedit.deserialize` by only deserializing the data once.
  * Makes some fields optional.
  * Cleans up the comments and a little of the code style.
Merge pull request #62 from ShadowNinja/command-prefix

Use "we-" prefix for commands
Merge pull request #61 from ShadowNinja/cleanup-serialization

Clean up serialization
Revert "Use "we-" prefix for commands"

This is currently being discussed, see #62.
This reverts commit 1024eace6f342a340ef84583b2c0c97d657ad326.