Added correct tie tube dimensions from the appendix of Schnitzler et al. 2007 ("Nutronics Models and Analysis of the Small Nuclear Rocket Engine (SNRE)")
Removed custom colors from plotting since the big plots at the end don't use them anyway.
Added a question about correct openmc file structure
Fixed a typo in .gitignore (.pynb_checkpoints/ --> .ipynb_checkpoints/)
This PR addresses issue #5
This PR closes issue #5