Include stdio.h in mrbconf.h instead of C extension sources.
Modify API configuration.
  C API mrb_p() is always callable.
  - But it will do nothing when ENABLE_STDIO is not defined.

  Kernel#__printstr__ is always callable.
  - But it will do nothing when ENABLE_STDIO is not defined.
Make some printf enclose in #ifdef ENABLE_STDIO.
Add accessor: version, description, summary, homepage.
Merge pull request #946 from monaka/pr-add-more-accessor-to-mrbgem_spec

Add accessor: version, description, summary, homepage.
Merge pull request #947 from monaka/pr-cleanup-stdio-calls-20130304

Cleanup stdio related.
Skip end of loop in mrb_sym2name_len
Remove RB_GC_GUARD(x) macro. See also mruby/mruby#948.
skip empty OP_STRCAT
Merge pull request #950 from monaka/pr-remove-macro-RB_GC_GUARD

Remove RB_GC_GUARD(x) macro.
Merge pull request #949 from mattn/find_symbol

Skip end of loop in mrb_sym2name_len
Replace tabs with spaces
Add include guard in node.h
Merge pull request #952 from kano4/master

Add include guard in node.h and Replace tabs with spaces