Propage call hook helper()

- Modifies call_hook_helper() to allow executing the given string or return the formated string.
- Uses call_helper() on every subAction call.
- Normalizes $sub_actions and other variations to camelCase $subActions

oh and fixes #1895 
Seems a bit longer and could be confused with call_user_func_array()  In theory, I would like all mod authors to use this on their own modifications.