Add domain model for the exchange protocol
Move main window to a new package
Introduce the concept of application view
Introduce a view selector
Introduce CSS for the wizard
Move multisig deposit creation to TransactionProcessor
Minimize the impact of Transaction being mutable
Merge pull request #178 from sortega/task/41_abstract

Introduce untested domain model for the exchange protocol
Require at least one view in ApplicationScene
Merge pull request #179 from sortega/task/54_main_view

Introduce views and CSS into the UI