Re-add trySetBlockAndMetadata helper method for adding mod events. Closes #1207

Unlike setBlock(), this method sends Bukkit events (with a fake player if
necessary) and can be cancelled. Intended to help porters add missing events
to ported mods (e.g. BuildCraft).

Note this method is experimental and subject to change or be replaced in the
future; for more information see the original commit:

MinecraftPortCentral/MCPC-Plus@43c402f33f6b7790cd05549e731e797af5be413a