Allow creating error trees #7
Description
Currently, it is possible to collect errors into a container (e.g. Vec). However, the user would have to create a wrapper for that to implement Error on, so that it can be turned back into a NeuErr. This NeuErr also does not allow accessing inner errors' machine attachments. And finally it might also be inefficient use of memory?
As a solution there could be a constructor for NeuErr, e.g. tree or combine that gets a new root message and a vec of source errors. However, it is not yet clear how internal storage should be handled and what exact behavior is wanted regarding combination of attachments and context.