Move Hash#values_at to mruby-hash-ext gem.
Move comments from hash.c to hash.rb.
Add more test cases for test coverage.
Remove mrb_hash_lookup() as no one uses it. Use mrb_hash_get instead.
Merge pull request #1237 from monaka/pr-cleanup-hash

Cleanup hash
mirb should handle exception from inspect; close #1238
Merge branch 'master' of github.com:mruby/mruby
Implement fallback print method for testing environment in case mruby-print GEM wasn't included.
Move declaration of kernel to the beginning of the method
[doc] Add minimal build configuration

In relation to #1225.

Adds a minimal build configuration for libmruby which contains as less as possible.
Merge pull request #1239 from bovi/fallback-print

[TestEnv] Fallback print method
Merge pull request #1240 from bovi/patch-1

[doc] Add minimal build configuration