Simplify. Temporary variable "i" is removed.
Extract stack zero filling to stack_clear(). Porting evelopers can optimize by replacing to memset() on their own risk.
Add null check
Cut off eval_test from main
Merge pull request #1003 from kano4/pr-add-null-check

Add null check
Merge pull request #1004 from kano4/pr-cut-off-eval_test

Cut off eval_test from main
Merge pull request #996 from iij/pr-systemcallerror

mrb_sys_fail raises an instance of (subclass of) SystemCallError if we have it
Merge pull request #1000 from iij/pr-set-data-type-asap

DATA_TYPE must be set as soon as possible
Merge pull request #1002 from monaka/pr-extract-stack-zero-filling

Extract stack zero filling into new function.
Merge pull request #1001 from monaka/pr-add-type-check-in-mrb_str_to_cstr

Add the type check in mrb_str_to_cstr().
Remove compiler warning
Define type mrb_bool. It is typedef-ed to _Bool on C99, unsigned int on MSVC.
It is safer than applying 1bit bit-fields to signed int.

For forward compatibility, you should substiture only 1 or 0 for the variable typed mrb_bool.
Merge pull request #1005 from mattn/remove_warning

Remove compiler warning
Merge pull request #987 from monaka/pr-clean-up-parse.y-20130312

Clean up parse.y.
remove PARANOID from comments
Merge pull request #993 from monaka/pr-cleanup-symbol.c-20130312

Cleanup symbol.c.
symbol length make size_t from mrb_int; cancel #993 monaka/pr-cleanup-symbol.c-20130312
use size_t for string length C API
use mrb_int as possible based on a patch from @monaka; close #994
Merge pull request #997 from monaka/pr-add-type-mrb_bool_t

Define mrb_bool_t.