use the new specifier b instead of o
supress cast warning on C++.
Fix disappearance of command_call in case of statement without parentheses.
mrb_field_write_barrier paints also gray in the major collector.
These objects will be traversed after a minor collect cycle.
check if array shrinks in each block
check if array expands in each block
save/restore arena index in mirb; close #740
Merge pull request #744 from authorNari/fixed-field-write-barrier

mrb_field_write_barrier paints also gray in the major collector.
Merge pull request #739 from cremno/use-b-specifier

Use new mrb_get_args binary specifier.
Merge pull request #742 from mattn/supress_cast_warnings

supress cast warning on C++.
Merge pull request #743 from iij/pr-fix-masgn

Fix disappearance of command_call in case of statement without parentheses
Clear all old flags, even if we change the gc mode during the major gc.
fixed wrong loop termination introduced by 79d38c4
Merge pull request #745 from authorNari/clear-old-flag-to-change-gc-mode

Clear all old flags, even if we change the gc mode during the major gc.
Merge branch 'master' of github.com:mruby/mruby
Modify handling of `bodystmt`.
Modify handling of OP_ENTER.

If `argc` is `-1`, `block` parameter is sometimes overwritten.
Add test for issue #750.
Modify handling of Quoted non-expanded literal strings.
Add a test for quoted non-expanded string literal.