Remove spaces in end-of-line.
Fix Numeric#pow behavior.

 * Before

2 ** -1 #=> 0

 * After

2 ** -1 #=> 0.5
Add test for Numeric#pow.
Merge pull request #2562 from cubicdaiya/issues/pow_flo

Fix and add test for Numeric#pow behavior.
Merge pull request #2561 from cubicdaiya/issues/space_EOL

Remove spaces in end-of-line.
printf: cast variables to the expected type

%x expects unsigned int and %p expects void *

GCC emits a diagnostic about %p/void* in pedantic mode:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26542
use MRB_STRINGIZE

It's defined in mruby/version.h which gets included in mruby.h, so it's
safe to use.
remove unused MSVC strtoll fallback
Merge pull request #2564 from cremno/use-mrb_stringize

use MRB_STRINGIZE
Merge pull request #2563 from cremno/printf-cast-variables-to-expected-type

printf: cast variables to the expected type
Merge pull request #2565 from cremno/remove-unused-msvc-strtoll-fallback

remove unused MSVC strtoll fallback
Remove discareded NULL checks.
Use mrb_malloc() instead of mrb_realloc().
Add a missing space after ",".
Merge pull request #2566 from cubicdaiya/issues/null_check

Remove discareded NULL checks and use mrb_malloc() instead of mrb_realloc().
Merge pull request #2567 from cubicdaiya/issues/space_after_comma2

Add a missing space after ",".
Fix error handlings for fprintf().
Fix error handlings for fputs().
add write barrier to env on pop call info poped. #2525
Merge pull request #2569 from dycoon/issue2525

add write barrier to env on pop call info poped. #2525