[PATCH] add lzma and xz to unpack plugin

[Zbigniew Luszpinski]

> that is the logical succession of my point, however, I really thing that 
> this move should START by making a plugin in the xz/lzma modules, not 
> the other way around.
> 
> stop bickering, write a plugin, it's easy, and any dev can commit it to 
> moonbase. :P
> 
> Auke

OK. I wrote and commited xz plugin.
bzip2, gzip and tar also should be converted to plugins?

Zbigniew