neveredit
This is an import of an old sourceforge project. Neveredit is an editor for Bioware's Neverwinter Nights game.
It also includes all the low level libraries and a command line tool to read and write the binary format files that the game uses.
I have no idea whether you can still get the actual editor to run, but I wanted to make the code more easily available. I suspect it wouldn't be hard to get the libraries and command line tool to run.
Note that this used an external open source Neverwinter Nights script compiler written in C - not included here.