Add copy() method to ThermalNetwork class

[jnettels]

I had cases where I wanted to copy a dhnx.network.ThermalNetwork() object.

I would be able to call new_network = copy.copy(network) on a network object. But then the DataFrames inside the network.components dictionary would not actually be copied. Instead both instances of the dict would point to the same DataFrames. (This is called a shallow copy, I think?)

This is bad if we want to manipulate the DataFrames but keep a backup of the whole network to restore later.
I solved this by writing a custom copy method:

def copy_dhnx_network(network):
    """Create a 'useful' copy of the ThermalNetwork object."""
    new_network = dhnx.network.ThermalNetwork()
    new_network.components = dhnx.helpers.Dict({
        key: df.copy() for key, df in network.components.items()
    })
    new_network.sequences = network.sequences.copy()
    new_network.results = network.results.copy()
    if network.timeindex is not None:
        new_network.timeindex = network.timeindex.copy()
    if network.graph is not None:
        new_network.graph = network.graph.copy()
    return new_network

It works for me, so I would like to propose it as a proper copy method implemented in the code. But I am not sure if that is the right way, and if that would have to be called copy(), __copy__(), or if it would actually be a deepcopy()?

Any suggestions?