Everything in predict method but `name` needs to be a named argument

[zeke]

When attempting to specify type and help without names:

@cog.input("seed", str, "A random seed", min=0, max=1000, default=None)

The following error is produced:

E   TypeError: input() got multiple values for argument 'default'

[bfirsh]

This feels like correct behavior to me -- we don't want users to depend on a particular order for arguments, and it makes it harder to read. Related to #205

[zeke]

If this is the correct behavior, then I think we should update the method signature docs to reflect that, as the first three arguments here appear to be positional:

@cog.input(name, type, help, default=None, min=None, max=None, options=None)

Does that make sense?