- build all tools using the Makefile and place them in ./build
- add copyright header to Makefile
- premix/readme.md edited to fix some errors, improve descriptions and
document Makefile usage
- link the Premix documentation in the main README.md
- also build `hunter` in the nimble tests
- refactored the file and directory search so all debugging tools can be run
from the top-level dir like this: `./build/<tool> ...`
- write all JSON debugging data in the current directory
- add JSON files generated in the top-level dir to .gitignore
- Nimbus now exits with an exception after dumping debug data and
running `premix` on it