Current system has many types of signals for views, which isn't plugin friendly. New system has only three signals and three corresponding methods for interacting with views:
1) selectByObject - for all signals that need MyMoneyObject only
2) selectByVariant - for all non-standard signals, which cannot be easily converted to MyMoneyObject
3) customActionRequested - for signaling some event, e.g. printing

New system, besides object, requires to specify intent of the signal. This comes in handy at synchronizing accounts between investment and ledgers view.

There is no more setDefaultFocus(), refresh() and updateActions(const MyMoneyObject&) because they were be replaced by above mentioned signals/slots and the interaction with views is thus more coherent.

Differential Revision: https://phabricator.kde.org/D11720