Let expr
There are a whole bunch of changes in let-expr, but these are the main differences:
- Added and tested (let) expressions
- Basic list manipulation
- Refactored
stacker_runto be faster and more readable - Basic arithmetic operations
- Removal of dead code for unimplemented "build" mode
- Lots of tests
- Automatically-reallocating strings in dynstring.h
- More documentation, including a man page