Merge branch '8.1.x' into tzhelev/fix-5520-8.1.x

Author: kdinev

ROADMAP.md

@@ -8,6 +8,9 @@
 2. IgxGrid row and cell selection modes [#4989](https://github.com/IgniteUI/igniteui-angular/issues/4989)
 3. Fluent Theme [#5335](https://github.com/IgniteUI/igniteui-angular/issues/5335)
 4. Drag and Drop enhancements [#5319](https://github.com/IgniteUI/igniteui-angular/issues/5319)
+5. Multi-View Calendar + Range DatePicker [#4282](https://github.com/IgniteUI/igniteui-angular/issues/4282)
+6. Custom grid row selector templates [#4998](https://github.com/IgniteUI/igniteui-angular/issues/4998)
+7. Per-column Filtering Strategies [#5323](https://github.com/IgniteUI/igniteui-angular/issues/5323)
 
 ## Going down the road