This tool, as the name clearly doesn't imply, is a block inserter designed to replace the dated BTSD. It is backwards compatible with BTSD and will upgrade your ROM when using the tool. The readme has full details on benefits, and thanks to Alcaro for writing the included GUI. The GUI is much slower to use in my opinion but does exist. Use the GUI at your own risk.
Simple blocks, for example Mario-only, can be created with Blockreator.
While the bugfix and the added offset are definitely appreciated, would it be possible to make the wallrun offset optional, like how BTSD used db $42 for the corner offsets?
Remoderating every block to add the wallrun offset and somehow update Blockreator to add a JMP to something only very few blocks will ever, ever use doesn't seem like a good way to spend ROM space.
I know I'm the one that suggested you to merge it, but I didn't actually think about what that would entail. I think keeping it in GPS but making it optional per-block is the way to go (and Alcaro agrees).
You can feel free to resubmit the other bugfix for the time being, though!
Here's a link to the whole thing if you don't have it any more.