Improve script check for number of args.

Remove the need for specifying check_argcount=False if function uses
*args.

expected_args is now a 2-value tuple with lower and upper range of
argument counts.

Also, looks like a bug in calc if there were defaults.

Commented print string left in so correct range can be verified if
needed.
Merge branch 'Sophist-UK-sophist_better_script_functions_num_args_check'
Use namedtuples for repeated access to the same elements

The position of the elements int he tuple have a meaning, this helps
understanding it when reading the code.
Reorder imports
Use None to denote a missing upper bound for script function arguments
Remove a commented print statement