Use MRB_IREP_ARRAY_INIT_SIZE macro. It should be configurable since it is possible to reduce RAM size.
implement heredoc
delete trailing space
use mrb_int for RString len
Merge pull request #884 from monaka/pr-use-MRB_IREP_ARRY_INIT_SIZE-macro

Use MRB_IREP_ARRAY_INIT_SIZE macro.
Merge branch 'heredoc' of https://github.com/FUKUZAWA-Tadashi/mruby into FUKUZAWA-Tadashi-heredoc
applied a patch from @cremo to support MSVC
allow reserved word for heredoc terminator