Fix mrb_fix2str() to enable handling some negative values correctly. This fix is based on @cremno's hack. It will fix #869.
Cosmetic changes. Just added empty lines.
Remove a comment at an unsuitable place.
Add a comment.
Fix an underlying bug. flodivmod() will be crashed in case ((y == 0) && ((divp == NULL) || (modp == NULL))).
Cleanup shift operations.
Merge pull request #873 from monaka/pr-cleanup-numeric-20130223

Clean numeric.c up.
Merge pull request #872 from monaka/pr-fix-mrb_fix2str

Fix mrb_fix2str().