Remove old Bukkit entity adapter classes. (reverted from commit b461f44db809674123639378355f245d5d9c9344)

CraftBook uses some of these classes.
Disable first time help message for now.
Remove Trove usage temporarily due to shading issues with Gradle build.
Fix WorldEditPlugin assuming that worlds are an instance of BukkitWorld.

Fixes WORLDEDIT-3168.
[Forge] Change compareTo() for commands to fix a Comparable contract issue.
Clean up Javadocs for the blocks.* package.
Code clean up, add preconditions, and correct Javadocs.
Rewrite session code and add support for persistent sessions.
Fix checkstyle error due to recent cleanup.
Fix undo and redo broken by a precondition.
Add Perlin, ridged multi-fractal, Voronoi noise generators via libnoise.
Add noise functions to the expression evaluator.
Update build files for noise library.
Add "=expression" mask.

i.e. =perlin(0,x/2,y,z/2,0.05,3,0.8)<0.1
Add noise library to allowed imports.
Refactor RegionSelectors so limits are passed in during selection.
Improve how //sel prints its available modes.
Fix ForgeWorld's equals() being very broken.
Add //sel -d <type> to set a default region selector type.
Clean up and removal of some old exceptions.