cc/mruby: add sample/04_class
cc/mruby: modify duplicate include
cc/mruby: add sample/05_define_method
cc/mruby: sample/06_class_struct_mutable
cc/clearsilver: add sample/01
cc/clearsilver: add sample/02
cc/mysql: add select sample
cc/mysql: add isql sample
add .gitignore