Allow variables to be created within python

I'd like to be able to create variables like this:

```
ca(x?)
```

or possibly this:

```
ca(b!1),CaM(c1!1)
```

in python programatically. I propose using a combination of lists and dicts to describe variables. e.g.

```
[{"ca": [{"x": "?"}]}]
```

and

```
[{"ca": [{"b": "1"}]}, {"CaM": [{"c1": "1"}]}]
```

would describe the above Kappa strings.
