Implement C API mrb_notimplement

Fix mrb_iv_check function decleration

Modify Arduino build config for IDE >= 1.5.7

%zu format is not supported by MSVC

Arduino IDE >= 1.5.7 Changed ARDUINO_PATH from `Contents/Resources/Java` to `Contents/Java`, mentioned in #2632

Add padding bytes before iseq block that may be used as mrb_code[].
Note that dumped mrb format has changed.

Based on a patch from kimu_shu <alfvegardrisc@gmail.com>

Under cygwin host, ncurses.a is only available instead of termcap.a.

avoid wrong ArgumentError from mrb_get_args() when surrounding method takes more than one argument; ref #2627

Handle Array#[float, int] Close #2626

Add kernel#Integer

Refactor for_body func

Fix indent

Replace int with mrb_bool in parse_string func

Replace int with mrb_bool in local_var_p func

Refactor yylex func

Refactor mrbc_context_new func