How Commands Are Interpreted (Part Two)

This is how commands are interpreted in mpw-shell.

1. Join lines and remove # comments
2. parse control structures - begin/end, ( ... ), for/end, loop/end, ;, |, ||, &&;
3. replace variables (and someday subshells)
4. split into tokens, remove quotes and escape characters
5. process i/o redirection
6. execute the command (builtin or external)