[ACA-1078] next/prev navigation for the Viewer (#187)

* basic navigation through the folder

* carousel mode for libraries

* code polishing

* save and restore sorting settings

* get user sorting preferences into account

* sorting fixes

* full test coverage

src/app/components/files/files.component.html

@@ -91,7 +91,7 @@
                 [attr.class]="documentList.isEmpty() ? 'empty-list' : ''"
                 [loading]="isLoading"
                 [node]="paging"
-                [sorting]="[ 'modifiedAt', 'desc' ]"
+                [sorting]="sorting"
                 [allowDropFiles]="true"
 
                 [contextMenuActions]="true"
@@ -100,6 +100,7 @@
                 [selectionMode]="'multiple'"
                 [imageResolver]="imageResolver"
 
+                (sorting-changed)="onSortingChanged($event)"
                 (node-dblclick)="onNodeDoubleClick($event)"
                 (node-select)="onNodeSelect($event, documentList)">