backup
remove the apply of GC
Restore the use of garbage collection
Merge branch 'feature-gc-split' into develop
Improve the define operator for accepts pretty function define form

The pretty function define form is something like:

(define (plus1 n)
  (+ n 1))

instead of:

(define plus1 (lambda (n) (+ n 1)))
Merge branch 'feature-define-fn' into develop
Move the function `make_compiled_proc' from file `compiler.c' to `object.c'
Reimplement function `pair_conc' in file object.c

And use macro `seq' in functions `compile_arguments' and
`compile_assignment' instead of the original `pair_conc' function.
Move the definition of function `make_primitive_proc' into file `object.c'
Misc modifications
Interrupt the interpreter when encounter end of file