Use BlockCommandSender for dispatching Command block commands

Also allow commands that don't start with a / to match vanilla behavior
Implement API for ambient mob spawn limit. Add spawn-limit.ambient to
bukkit.yml. Adds BUKKIT-2765
Fix NPE when blowing up an item frame. Fixes BUKKIT-2763
Add inventory and slot types for new containers. Fixes BUKKIT-2741
Fire HangingBreakEvent when explosions remove hanging entities. Fixes BUKKIT-2764
Updated version to 1.4.2-R0.1 in pom.xml for Beta.
Updated version to 1.4.2-R0.2-SNAPSHOT for development towards next release.
Change ItemFrame to actually provide a defensive copy. Fixes BUKKIT-2784

If a defensive copy is not used in the API, changes to the item are
reflected in memory, but never updated to the client. It also goes
against the general contract provided in Bukkit, where setItem should be
the only way to change the underlying item frame.
Add CraftArt mappings for Wither. Fixes BUKKIT-2667.

The static assertions are not normally evaluated in the JVM, and failed
to fail when the enums went from size 25 to size 26. This meant missing
values would not be detected at runtime and instead return null,
compounding problems later. The switches should never evaluate to null
so will instead throw runtime assertion errors.

Additional unit tests were added to detect new paintings and assure they
have proper, unique mappings. The test checks both that a mapping
exists, is not null, and does not duplicate another mapping.
Delegate recreateStructures to nms provider. Fixes BUKKIT-2760

This was a miss when updating to 1.4.2
Fix compile issue with chunk generation.
Improved the potion test to detect missing PotionType values.
[Bleeding] Fix mistranslation affecting time of the server vs time of day.
Fixes BUKKIT-2797
Migrate world data with world when switching from vanilla Minecraft to
Bukkit. Fixes BUKKIT-2816 and BUKKIT-2760
Updated version to 1.4.2-R0.2 in pom.xml for Beta.
Updated version to 1.4.2-R0.3-SNAPSHOT for development towards next release.
Update CraftBukkit to Minecraft 1.4.4.
Correct digging behavior. Fixes BUKKIT-2780

If a block is air we return immediately so miss the cleanup work that would
normally happen in this case in vanilla. This causes us to get in to a
situation where, due to odd packet sending from the client, we never
properly stop an attempt by the client to break a block and thus it
eventually breaks.

We also use our own variable for block damage and never sync it up with the
vanilla one so damage reporting to other clients is not always correct.
Add EntityFallingBlock from mc-dev
Potentially fix glitch with falling entities.

When a block creates a falling entity the block is not immediately removed
from the world. Instead, the falling entity is responsible for removing it
but only if the block still exists. Due to certain piston mechanics it is
possible to move the block before this check happens and thus the block is
not removed. This should be fine as the entity will kill itself in this
situation. However, the code does not stop here and continues running the
rest of the entity logic which includes either placing a block in the world
or placing a block item in the world depending on the circumstances.