Change-Id: I2cb7bbd9a6d9da28116ba9dd9cec4e60525444e2
Change-Id: I6f4e37b293aac9054a768f9d692b914f52d42756
Change-Id: I59d2e15b297b6ca2d5eee1a6dee642bdb01a3839
This will fix issue #1621. It also adds tests for is_callable with c++11, c++14, and c++17. The fallback implementation was completely broken so I rewrote it so it pass the tests as well. This should be used instead of PR #1631.