remove unused imports

move ws handler to websocket package

add WebSocketMessage entity structure
add basic feedback logic
add tests for Feedback messages

These tests exercise the happy path. If needed, negative tests could
be added in the future.

Reverts 8ad7cd84

This fixes issue #33. However, it is still unclear why different
beans are shared between test and production code.

Both the RoomRepository as well as the CacheManager beans were
not shared between test and production classes. Hence, when we
set up some mocks (or caches), the mocked values were not
present in the production classes.

We explicitly force instance sharing by applying the Singleton pattern.

Google shuts down its Google+ Sign-In.

See arsnova-backend#2.

Mock the correct method.

* Prefer simple IDs over entity types for method parameters
* Avoid use of obsolete v2 classes in service and repository layers
* Optimize imports

Consistently use singular for packages which contain mixed kinds of
classes. Moved a few classes to packages that better fit them.

The Java default of handling .properties files as ISO 8859-1 encoded is
not contemporary anymore.

Renamed UserAuthentication to ClientAuthentication and moved it to v2.
API v3 uses its own model.

For now, only Answer and AnswerStatistics migrations are tested.

Additionally, remove obsolete VisitedRoom repository and renamed
VisitedRoom references to RoomHistory.

Additionally, remove obsolete MotdListRepository.

Implemented a customized WithMockUser and
WithMockUserSecurityContextFactory to mock an Authentication with User
and UserProfile.

* AuthenticationProvider-agnostic User object allows access to common
  user attributes: userId, loginId, authProvider, etc.
* Auto-create UserProfiles for external accounts
* Use userId (instead of loginId) for permission checks
* Use custom implementation for Pac4j integration
  (remove org.pac4j.spring-security-pac4j)
* Move authentication logic from controller to service layer
* Remove user room role handling
* Rename targetDomainType 'session' to 'room'

Moved PI timer logic to its own service. The implementation for room
owner changes has been removed for now.

A new service, repository and entity have been introduced to handle file
attachments to other entities. Attachments store meta data about the
file. The file upload is not yet implemented. It is planned to abstract
the storage handling to allow the support for different storage
solutions (local file system, database, cloud).

Marius Renner authored 7 years ago and Daniel Gerhardt committed 6 years ago

Cast int to double before division to avoid truncation of the division
result. Changed corresponding test so that it fails with the old
implementation.

Cherry-picked and backported from GH-52.