Support local variables information dumping.
Implement Kernel.local_variables for testing dumped local variables information.
Remove `lv_len` and use `nlocals - 1` instead.
Check that `lv`'s length is always `nlocals - 1`.
Implement Struct#values_at and Array#values_at .
Add API `mrb_get_values_at()` to mruby/range.h .
Update time.c

miss __MINGW32__ macro check
Merge pull request #2170 from windwiny/patch-1

Update time.c
Refactor rshift
Merge pull request #2172 from suzukaze/refactor-numeric.c

Refactor rshift
Delete unused variable in Array#delete_if
Fix indent
MSVC: treat implicit function decl. as error

As equivalent to GCC's `-Werror-implicit-function-declaration`.
add namespace prefix to `dump_irep`
mruby-math: define and use `Math::DomainError`

Domain errors are detected as per ISO C99 and may differ from CRuby.
fix condition for the rest of input

the input must rest the length of a string to be peeked at least.
fixes parse error at embedded documents by string eval, and `-e`
command line options.
fix embedded documents

tabs are allowed after `=begin` and `=end`.
raise `SyntaxError` if no =end is found.
fix char after `=end`

skips() advance after the string skipped.
skip to the next line and reset column after `=end`
count skipped line numbers
Merge pull request #2173 from suzukaze/delete-unuse-variable

Delete unused variable in Array#delete_if
Merge pull request #2174 from suzukaze/fix-indent

Fix indent