fp/secd: SECD machine draft
Cleanup
Cleanup
fp/secd: 2+2 works!
fp/secd: secd_eq draft
fp/secd: CONS/CAR/CDR work, execute stdin

1) CONS/CAR/CDR work fine now;
2) added a SECD parser;
3) can execute a list of SECD ops from stdin:
    $ echo "LDC 2 LDC 2 ADD" | ./secd
fp/secd: working ATOM
fp/secd: parsing nested lists fine

Now "LDC (1 2)" is a correct input
fp/secd: SEL/JOIN almost working
Merge branch 'master' of github.com:EarlGray/language-snippets
fp/secd: SEL/JOIN work
fp/secd: can continue after JOIN
fp/secd: small improvements
fp/secd: added SUB/MUL/DIV/REM. AP/RTN/LDF

- AP/RTN/LDF work
- added test1.secd
Refactoring: Now NIL is secd->nil, not NULL
fp/secd: DUM/RAP opcodes, not tested yet
fp/secd: DUM/RAP work, recursion works.

Added two tests files, one of them is SECD programs for factorial(4).
fp/secd: test1.secd fixed
OS X compilable
Tail recursion