use Kernel#__send__ insteard of Kernel#send
Implement Struct#to_h .
Added dump_irep in header.
Merge pull request #2162 from ksss/__send__

use Kernel#__send__ insteard of Kernel#send
Merge pull request #2163 from take-cheeze/struct_to_h

Implement Struct#to_h .
Implement header search for gcc and clang.
Use header searcher to find readline and linenoise.
Merge pull request #2164 from scalone/public_dump_irep

Added dump_irep in header.
Merge pull request #2165 from take-cheeze/header_searcher

Implement header searcher to use readline in mirb if possible.