Rename TntFile to TntReader
Rename SctFile to SctReader
Implement IDisposable on TntReader
Implement IDisposable on SctReader
Remove direct stream references from TntReader and SctReader
Add finalizer to SctReader
Implement IDisposable on TntWriter
Change char to byte in gaf frame header
Refactor gaf reading code to not create BinaryReaders
Fix crash when loading GAFs containing zero size frames