I replace 0 with NULL because struct pointer be should set NULL in.
I replace 'Pre-Conditions' with 'Preconditions' because the former is a wrong word.
Remove pop that was done when not a return val
Add a couple splat tests
Merge pull request #1417 from suzukaze/fix-doc-mrbgems

I replace 'Pre-Conditions' with 'Preconditions' because the former is a ...
Merge pull request #1416 from suzukaze/refactor-object-ext-object.c

I replace 0 with NULL because struct pointer be should set NULL in.
Merge pull request #1421 from carsonmcdonald/fixfor1419

Remove pop that was done when not a return val
forget to re-initialize target_class for top-level eval; close #1418
Merge branch 'master' of github.com:mruby/mruby