Adds documentation for MRuby::GemBox usage
move mrb_shared_string definition to src/string.c
fix mrb_string_shared memory leaks
rename hash related gc functions
Merge pull request #1220 from arton/master

add extern funcs declaration and casts for cimpiling C++ compiler
Merge pull request #1219 from cadwallion/gembox_docs

Documentation for MRuby::GemBox usage
fix memory leaks in mruby-random
change return value of mrb_free from void* to void
use mrb_free to free random state
always use unsigned int as mrb_bool even in C++
Revert file access mode to 0644.
Merge pull request #1221 from monaka/pr-revert-file-access-mode

Revert file access mode to 0644.
use uint8_t for mrb_bool instead of unsigned int; close #1222
Merge branch 'master' of github.com:mruby/mruby
remove our own prototype for sprintf(); ref #1223
rename mrb_to_id to mrb_obj_to_sym since symbol is nothing to do with identifier in mruby
remove unnecessary intern; access to non-member cause IndexError