Addition of permissive logical default parsing

[lukaswittmann]

Allow permissive logical default parsing for formats like "1/0", "yes/no", "on/off", instead of "true/false".
A todo comment was added in #17.

[chselz]

I am not sure if i really understand what you desire here. This yes/no stuff is in my experience more something what you would implement in a while loop with a read statement to ensure that the correct thing was entered.
On the other hand i don't see a use case for making a flag like this : --opt yes or --opt no as the options because just setting the flag itself sets the logical to the correct value (--opt) using the store_true or store_false action. If something like this is desired the use should themself make an if/case statement in their code like this

if (opt == "yes") then
    variable = .true.
else
    variable = .false.
end if

or do you mean that this is the goal

--verbose → .TRUE.

--verbose=false → .FALSE.

--verbose=0 → .FALSE.

meaning one would need to change the parsing of logicals. This would probably require the setup of a new action type. Something like store_true_permissive

Is this what you intended?