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
Implement GEM dependency check
Todo is actually already finished :-)
Merge pull request #1241 from bovi/add-gem-dependency-check

[mrbgems] GEM Dependency Check
consider gem version to be 0.0.0 unless specified
consider empty version requirements as >= 0.0.0
fix regexp warning: character class has duplicated range
remove unused variables
Merge pull request #1244 from NARKOZ/regexp-warning

fix regexp warning: character class has duplicated range
Print mrb_value instead of RClass*
Merge pull request #1247 from carsonmcdonald/issue1246fix

Print mrb_value instead of RClass*
Merge pull request #1245 from NARKOZ/fix-warnings

remove unused variables
Merge pull request #1242 from schmurfy/gem_version

consider gem version to be 0.0.0 unless specified
fix indentation
Rename parameter names for mrb_yield
Merge pull request #1248 from ktaobo/rename-yield-param

Rename parameter names for mrb_yield