Abstract network implements concrete type logic

[hellkite500]

The build_forcing_sets function in the abstract interface is implementing logic for the concrete types by switching on the configuration/input parameters provided in the config file.

This is a serious anit-pattern. The abstract functions should be @abstractmethods and the appropriate subclasses should implement overloaded functionality based on the dynamic type as needed.

This also seems to have crept in with other functions such as nex_files_to_binary. Though this function isn't a member of the abstract class, it really belongs to the hy_features/ngen utilities and probably shouldn't be in the AbstractNetwork module.
Similarly, but could possibly be argued as generic functionality, initialize_warmstate_preprocess looks like it may be encroaching as well.