Use resolve dimension methods in implicit state variable creation

[tclose]

Using the shorthand version of Dynamics classes you do not need to specify the state variables as they are determined from the time derivatives. However, if you need to specify the dimension of the state variable you currently need to specify it explicitly. Since I have now written methods to resolve the dimension of expressions it might be possible to use them to determine the state variable dimension implicitly as well.

[DhanashreePetare]

I am interested to work on the issue. Can you please assign it to me.