Changes for version 0.20
- Advanced deprecation of _CALLABLE to "warn but work".
- Correctly refer to _CALLABLE being deprecated, not _CODELIKE.
- Add support for Tie::Handle objects to _HANDLE
- Add support for IO::Scalar objects to _HANDLE
- Add support for IO::String objects to _HANDLE
- Params::Util - Simple, compact and correct param-checking functions