This was requested by a forum user, and I thought why not.
It's a simple change to make since DiscIO already supports it,
and I assume command-line users know roughly what they're doing.
New dolphin-tool command: "header"
-b / --block_size
-c / --compression
-l / --compression_level
Informative RVZ/WIA header2 value "compression_level" is now a s32 instead of a u32, because negative compression is a thing.
Speaking of, it is now possible to use negative compression levels in dolphin-tool's convert command (not the GUI, though).
Admiral H. Curtiss