synchronization with library-service branch + constants are moved from Library to LibraryTree
Merge branch 'master' into multidirs

Conflicts:
	src/org/geometerplus/fbreader/library/FileFirstLevelTree.java
introduced BookWithAuthorsTree class
Merge branch 'master' into multidirs
synchronization with library-service branch
Merge branch 'master' into multidirs
AuthorListTree
Merge branch 'master' into multidirs
synchronization with library-service branch
Merge branch 'master' into multidirs
synchronization with library-service branch
Merge branch 'master' into multidirs