ISIS-939: simplified PersistenceMechanismInstallerAbstract and its subclasses, also PersistenceSessionFactoryDelegating, PersistenceSessionFactoryDelegate.

* Replaced PersistenceSessionFactoryDelegate#createPersistenceSession with #createObjectStore (other common functionality moved to PersistenceSessionFactoryDelegating).
* Don't pass ObjectAdapterFactory, AdapaterManagerSpi, OidGenerator into PersistenceSession; instead it can new these up (there is no variation in implementation nor state held in these components)
* Removed IsisObjectStoreLogger, IsisObjectStoreDelegating.
ISIS-939: more simplified of persistence sessions and object stores.

- deleted ObjectStoreSpi, just use ObjectStore (impl) directly;
- deleted AdapterManagerAbstract, not used
- deleted AdapterMapDelegator, not used
- for in-memory objectstore, renamed ObjectStorePersistedObjectsDefault (impl) to ObjectStorePersistedObjects (unextracted interface)
- renamed PersistenceSessionFactoryDelegate to ObjectStoreFactory
- renamed PersistenceSessionFactoryDelegating to PersistenceSessionFactory (unextracted interface)
- removed AdapterManagerSpi interface, just use AdapterManagerDefault directly instead.
- deleted AdpaterUtils, not used
ISIS-939: deleted the UpdateNotifier subcomponent.  Not used by any released code, and the same information (and better) is available in the IsisTransaction itself.
ISIS-939: simplified MessageBroker

- removed the defunct MessageBroker interface (in runtime)
- renamed MessageBrokerDefault to MessageBroker (unextract interface), now in metamodel
- removed #setApplicationError, since no longer used.
ISIS-939: deleted AdapterLifecycleTransitioner interface (performed no function).

Also: deleted unused/undocumented IsisServices service.
ISIS-939: simplifying PersistenceSession

- removing PersistenceSession#resolveField (introduce ResolveFieldUtil for scimpi to call), also from the *ObjectStore impls
- remove Persistor interface, instead PersistenceSession everywhere
- remove ToPersistObjectSet interface, instead PersistenceSession everywhere
- remove RecreatedPojoRemapper interface, instead PersistenceSession everywhere
- remove EnlistedObjectDirtying interface, instead PersistenceSession everywhere
- remove ObjectAdapterMemento#getTitleHint() and #captureTitleHintIfPossible()
- re-introduce MessageBroker's #getApplicationError and #setApplicationError
- remove ObjectAdapter#isTitleAvailable() and from PojoAdapter
- removed commented out lines in ResolveState
- simplify PersistenceSession (remove #mapRecreatedPojo, #remapRecreatedPojo)
- introduce PersistenceQueryFactory from PersistenceSession
- PersistenceSession creates IsisTransactionManager in its constructor
ISIS-939: clear the MessageBroker's applicationError field once read (functionality lost in previous refactorings).
ISIS-941: don't try to flush property changes from form for disabled properties.
ISIS-537: update to ToDoItem's layout to demonstrate labelAt facet.
ISIS-537 Write the 'type' HTML attribute even for invisible buttons with placeholder

https://trello.com/c/JwALpbYI/113-bootlint-error-always-set-a-type-on-buttons
ISIS-537 Add 20px under the entity (EntityPropertiesPanel) to make a clear distinction with the row for entityCollectionsOverflow

https://trello.com/c/3LYn12tx/115-a-bit-more-space-underneath-the-ok-edit-cancel-buttons
ISIS-537 Use .input-sm for the select2 input fields.

https://trello.com/c/f60AAQps/116-tiny-adjustment-to-spacing-on-select2-drop-downs
ISIS-537 Use NotificationPanel instead of FeedbackPanel

https://trello.com/c/OB0ja10z/111-replace-all-usages-of-feedbackpanel-in-the-addons-with-notificationpanel-for-consistency-with-isis
ISIS-537 Change the name of the theme chooser cookie to be more inline with the names of the properties
ISIS-537 Use Bootstrap grid offset classes instead of empty columns. Suggested by Bootlint 0.8.0
ISIS-537: removing a TODO:mgrigorov (comments only)
ISIS-537: moved markup and CSS for LinksSelectorPanelAbstract into its subclasses (CollectionContentsLinkSelectorPanel and EntityLinksSelectorPanel).
ISIS-537: moved impl of LinksSelectorPanelAbstract (.java) to subclasses.
ISIS-537: deleting LinksSelectorPanelAbstract, no longer used.
ISIS-537: render selector panel-specific CSS to ensure that unselected views are not shown.