Use an exception for unimplemented chunk and entry controllers

+ Remove ErrorController
Add a controller for unknown entries
Add support for loading compressed chunks

+ Add NSF.ReadChunk
+ Add Chunk.CompressedMagic
Remove an unnecessary namespace use
Handle some errors loading data

+ Add BadChunk
+ Add WeirdEntry
+ Add BadChunkController
+ Add WeirdEntryController
Update README for experimental crash 1 support