[validation] types and values for parameters not properly checked in editor/ second issue old value saved

@jdiefenbaugh : The editor presents some validation bugs

The editor seems to have unexpected behavior for validation of parameters.

A string value could be saved in a int8, and this is valid and could be saved in the json file.

A second issue comes from the fact that all parameters have their old value saved somewhere in the props or state history.

For example if we suddenly decide to change the parameter type from "string" to "int", the value "helloworld" will be kept as the value for the "int"