prepare for class_spy
prepare test of Crispy.stub_const
add test of Crispy.stub_const
(WIP) implement Crispy.stub_const
implement Crispy.stub_const
write document of Crispy.stub_const
delete non-used files
Incompatible change: move public modules into upper directory

I found we can't refer them by `Crispy::World` or
`Crispy::ReceivedMessage` after `include`-ing the top level  `::Crispy`.
So I renamed them into `CrispyWorld`, and `CrispyReceivedMessage`
adjust newlines
Merge pull request #11 from igrep/const-stub

Const stub