SimpleCrypt: Pocket Slide Rule Cipher

This is a simple and small cipher designed for quick text encryption by character substitution.

This cipher consists of:
- a case with multiple viewing window slits for the slides that fit inside
- a back slide of 3 staggered sequences and a line of code characters at the top
- 3 parallel slides that slot in perpendicular to the back slide, with a line of code characters on the left.

There are two files for the back slide, one that is whole (for large area printers) and s