don't use static class instances
Merge branch 'master' of https://github.com/mruby/mruby
Merge branch 'master' of https://github.com/mruby/mruby
Merge branch 'master' of https://github.com/mruby/mruby
Merge branch 'master' of https://github.com/mruby/mruby
remove compiler warnings.
Merge branch 'master' of https://github.com/mruby/mruby
Merge pull request #718 from mattn/remove_compiler_warnings

Remove compiler warnings
add mrb_check_hash_type
Merge pull request #720 from skandhas/pr-add-mrb_check_hash_type

add mrb_check_hash_type
Removed gem libraries in mrbc
Fixed mrbtest result numbers
Merge pull request #721 from masuidrive/remove_gem_libs_from_mrbc

Removed gem libraries in mrbc
Merge pull request #722 from masuidrive/fixed_mrbtest

Fixed mrbtest result numbers
Merge branch 'master' of https://github.com/mruby/mruby
remove mrb_str_each_line form src/string.c
Merge pull request #725 from skandhas/pr-remove-each_line

remove mrb_str_each_line
should be flatten.
build gems if build_config.rb is modified.
note about $MRUBY_CONFIG.