Add option to decay flowing lava. Adds MC-4631, #656.

Vanilla has a bug/feature where flowing lava decays
extremely slowly, as in hours/days/never. This change
adds a configuration option to bukkit.yml, which if set
to true (defaults to false for vanilla behavior):

mcpc.flowing-lava-decay: true

will cause a block update to be scheduled after the
random check did not remove the lava, therefore causing
flowing lava to decay at a rate comparable to its normal
flow rate.

For more details see: https://mojang.atlassian.net/browse/MC-4631

This change can be implemented in a mod, however, it requires
either a coremod or jarmod both which are not likely to be
compatible with MCPC+, since CB also edits the BlockFlowing class.
Hence this new config option.
Add null checks in onStruckByLightning, possible fix for #392
Add configurable block placement event simulation

Mods can override ItemBlock onItemUse/placeBlockAt, which bypasses
Bukkit's normal block placement codepath. The Bukkit BlockPlaceEvent
can be instead sent in World canPlaceEntityOnSide to cope with the
world protection bypass, however, the temporary block placement
can cause duplicate item drops with certain mods.

To support both situations, until something better can be developed,
the simulation is now configurable with the following new settings in
bukkit.yml's mcpc section:

simulate-block-place-event-IDs: a list of block IDs to whitelist/blacklist

simulate-block-place-event-default: a boolean, either:
 true: enable event simulation, except for block IDs listed above
 false: disable event simulation, except for block IDs listed above

These settings let you choose sending-events/not-duping, as appropriate:

- If you are seeing dupe item drops on block place, disable simulation
- If you are not getting block placement events, enable simulation
Fix ocelot spawning in jungle biomes. Fixes #703.

Restores vanilla behavior.
Fix another NPE with Mystcraft lightning. Related #392.
Merge pull request #1 from MinecraftPortCentral/MC147

Mc147