Create my lisp interpreter according to http://buildyourownlisp.com/
Licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0
http://creativecommons.org/licenses/by-nc-sa/3.0/
- Difference from original BuildMyLisp ***** S-expression include include atom and list, so the list is named "list" lval instead of "sexpr".
- Difference from original BuildMyLisp ***** Quoted expression not use "{1 2 3}" format, just use " '(1 2 3)" ** Since quoted expression also include atom, so link real expression lval to quoted expression lval