It's the Mozilla Public License (MPL) 2.0, which in effect is similar to the LGPL but without the annoying dynamic/static linking mess. So far, 100% of the code is mine and I have been seriously considering switching to the MIT license because I don't really care what my code is used for, for me it's really about the fun of programming. Also, thinking about licenses annoys me.
So really, you are free to use it to use it for whatever you need. At this point, I'm pretty sure I will relicense it soon, and also get rid of that annoying license prompt in the OS X bundle.
It's relatively easy to build, the main obstacle is the dependency on Qt. I build a static version of the qtbase5 libraries, and it's not as easy as I'd like to, and not completely integrated into my build system. Of course the command-line version does not need Qt. I guess you could pilot it from your own GUI instead.
The master branch is stuck into a messy, half-refactored state. After letting it rot away for some time due to lack of time and energy, I did force myself to fix it a few days ago and it's looking good now (even though I haven't pushed anything yet, gotta remove the remaining FIXMEs I littered around in my workspace). The maintenance branch is where the stable and working code lives, for now.