Refactored and documented SelectStudentPopupWindow
Changed the toTerm of one test
Enhanced the ViewModel so that the unit tests are successful
Merge remote-tracking branch 'upstream/develop' into issue#532

Conflicts:
	src/main/java/de/dhbw/humbuch/viewmodel/DunningViewModel.java
Refactored and documented ManualProcessWindow
Adapted Lending and ReturnView to fit the new windows
Merge pull request #553 from Junkern/issue#532

Issue#532
Changed BookManagement to TeachingMaterial
Merge pull request #554 from henningmu/issue#529

Manual Return Process
Merge pull request #555 from Junkern/issue#549

Changed BookManagement to TeachingMaterial
Merge pull request #556 from davvitt/issue#544-UpdateEvent

Issue#544 update event
reverted .project to previous version

due to unnecessary changes
Merge branch 'upstream/develop' into issue#557

Conflicts:
	src/main/java/de/dhbw/humbuch/view/BookManagementView.java
	src/main/java/de/dhbw/humbuch/viewmodel/BookManagementViewModel.java