Fix arena size check.
Move Math::TOLERANCE to mruby-math
Modification of CONTRIBUTING.md

Some minor fixes of the  CONTRIBUTING.md file.
Fix styleguide based on @cremno's input
Merge pull request #915 from bovi/patch-1

Modification of CONTRIBUTING.md
Merge pull request #914 from bovi/math_tol

Move Math::TOLERANCE to mruby-math
Adjust space
Merge pull request #917 from matsumoto-r/adjust_space

Adjust space
Merge pull request #913 from carsonmcdonald/arena_check_fix

Fix arena size check.
Remove unused structures.
Move the place of a curly bracket. This is just a cosmetic change.
Pluggable Struct
Add typedef to structures that have mrb_ prefix. Use typedef-ed type instead of struct directly.
Pluggable Struct
Merge branch 'master' into pluggable_struct
Gemify
Move mrblib for Struct
format some source code (class.c)
Merge pull request #919 from monaka/pr-use-typedef-names-as-possible

Use typedef names as possible
Merge pull request #921 from skandhas/pr-format-class-source

format some source code (class.c)