Added more clearance to docs

Specifying form inputs' names prefix in the Form Types Features documentation section
If a description is not provided use form label

It would be nice if there was no description the form label was used instead. In the future I think it would be even better to have the label as an header, and the description as 'additional' instructions.
added fix for doubled parameters
Parse JSM\Inline, fixes #372
Don't parse custom properties as classes. 

Sometimes instead real class name we can use custom handler name. Then this class can't be initialized and we will get this exception ```ReflectionException: Class custom_handler_name does not exist```
Test fixes.