Change handling of strings and objects TypeConverter
Change handling of strings and objects TypeConverter

Wrap constructors in a function that sees if it is an instance, if it
isn't tries to convert the object, and errors out if it can't.
Also require strings to be a string value

joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue