Added cSignEntity into API, added cChunkDesc:GetBlockEntity().

This fixes both #228 and #347.
Exported cJukeboxEntity to Lua API.

Ref. #228
Added cNoteEntity to Lua API.

Ref. #228.
Fixed growing issue with crops.
Merge pull request #349 from SamJBarney/master

Fixed growing issue with crops.
Removed BlockEntities' constructors from the API.

Plugins shouldn't construct block entities, rather, they will query them either from the cWorld (while playing), or from cChunkDesc (while generating).
Debuggers: Added the BlockEntity test harness when generating chunks.
Re-added rose to items.ini.
APIDump: Removed the BlockEntity constructors' docs.
cRoot::SaveAllChunks() doesn't wait for the save (deadlocks).

Rather, it only queues the save task onto each world's tick thread.
Removed cBlockEntity:CreateByBlockType() from the Lua API.

Plugins cannot be allowed to create block entities, that would result in memory leaks.
Debuggers: Removed the old OnChunkGenerated code testing the cBlockArea writing.
cChunkDesc::GetBlockEntity() re-creates block entity when blocktype doesn't match.
APIDump: Documented cChunkDesc:GetBlockEntity().