MSVC: treat implicit function decl. as error

Fix indent

Delete unused variable in Array#delete_if

As equivalent to GCC's `-Werror-implicit-function-declaration`.

Refactor rshift

Update time.c

miss __MINGW32__ macro check

goto STOP if ridx==0

On overflow, clear new stack space before mrb_raise

Remove use of define_singleton_method.

Implement header searcher to use readline in mirb if possible.

Added dump_irep in header.

Implement Struct#to_h .

use Kernel#__send__ insteard of Kernel#send

Space

Add doubling stack extend, as fix for #2016

Print file name and line number in codedump if available.

fix disabled stdio

define `resize_capa` as a function

remove `mrb_str_offset`

remove `DBL_DIG` fallback definition