<wtf: Get back the user param withing init func>

We forgot to retrieve the decorator, infile, method and pattern
withing the __init__ function of the WTF class.
<wtf: Remove unraised exception from _check_user_params doc string>

The _check_user_params function does only raise SystemExit when an
error is detected.
<wtf/arg_parse: Adds the -h option>

By using -h the program will return the usage