Add bzip2 compression

[tvb]

For a better compression ratio, turn side it is somewhat slower then gzip.

[gocom]

Yeah, it would create slightly smaller files. Like zlib, its optional extension, just not as popular.

If PHP just implemented its compressor extensions using interfaces. You could very easily use any compression option available with simple configuration flag. Unfortunately it doesn't and you have resort in nested conditionals, or write your own wrappers.

[gocom]

I've started writing compressor implementations that also covers regular plain text files. This then allows using the compressors for actual writing, replacing the two-step process.

[tvb]

Great news!