Add generator script to dependency so that it will regenerate C codes when it's modified.
mruby-struct: internal linkage for all functions
mruby-struct: use correct data types
mruby-struct: remove unused functions
remove mrblib/print.rb that only raise NotImplementedError; ref #2354
move IS_EVSTR macro that should be private to src/string.c
Release `mrb->atexit_stack` on `mrb_close`.
mruby-struct: implement `mrb_is_(local|const)_id`
implement `ISASCII` correctly
`ISSPACE` evaluates its argument multiple times
don't (re-)define `ascii_isspace` and `isascii`

`ISSPACE` and `ISASCII` can be used instead.
use uppercase US-ASCII ctype macros
partially revert 1a5841b for mirb

Fix compilation fail caused by GNU Readline and `ISPRINT`.
Also add missing `unsigned char` cast.
Merge pull request #2364 from take-cheeze/free_atexit_stack

Release `mrb->atexit_stack` on `mrb_close`.
Merge pull request #2365 from cremno/mruby-struct-function-changes

various mruby-struct function changes
reduce calling mrb_sym2name_len() from struct.c; ref #2365
Merge branch 'ascii' of https://github.com/cremno/mruby into cremno-ascii
git push origin masterMerge branch 'cremno-ascii'
Merge pull request #2359 from take-cheeze/src_gen_dep

Add generator script to dependency so that it will regenerate C codes when it's modified.