remove executable bit from include/mruby/dump.h file
Fixed self value in a block is changed with return value

fix #1504
Fix self value in a block is changed with return value for Fixnum, nil, instance variable.

Fix #1504
Merge pull request #1503 from digitaltom/master

remove executable bit from include/mruby/dump.h file
Merge pull request #1505 from ktaobo/return-breaks-self

Fixed self value in a block is changed with return value
refactor genop_peep(); ref #1505
rename node->filename to node->filename_index
remove unreferenced local variables caused by mrb_assert()