Fix #196; add type_check callback
Add tests for type_check callbacks
Rename "type_check_inputs" to "type_check"

This way the function name matches the callback name, like execute.
Add more extensive callback tests
Don't use new "%i[...]" syntax
Merge branch 'v1.3.0' into issue-196
Merge branch 'master' into issue-196
Use new RSpec 3 matchers
Run callbacks from #type_check
Merge branch 'v1.3.0' into issue-196
Update changelog