Add option to allow auto-detection for LZFInputStream, LZFFileInputStream

[cowtowncoder]

It would be nice to be able to do optional decompression, meaning that if input is detected to be LZF (as per signature), decompress; if not, read as is.

Since this is potentially dangerous feature in that it could hide corrupt data, it should be disabled by default, but could be enabled by user.
It should be supported both by regulard LZFInputStream and LZFFileInputStream.