update refactoring README.
ongoing refactoring. remove xml serilaization dll and moved those members.
remove Cadencii.Media.Midi and merge into Cadencii.Media.Base, renamed from Cadencii.Core.Media .
ongoing refactoring. more winforms removal.
ongoing refactoring. move some forms that are "portable" state to model dll.
ongoing refactoring. now we have our own DialogResult, less WF dependency.
ongoing refactoring. winforms dependency is gone from AppManager code itself.

Though it still depends on winforms as new DialogManager depends on it yet.