Introduce canMerge method on timeline style

Riot/Modules/Room/TimelineCells/Styles/Bubble/BubbleRoomTimelineStyle.swift

@@ -49,6 +49,10 @@ class BubbleRoomTimelineStyle: RoomTimelineStyle {
     func canAddEvent(_ event: MXEvent, and roomState: MXRoomState, to cellData: MXKRoomBubbleCellData) -> Bool {
         return false
     }
+
+    func canMerge(cellData: MXKRoomBubbleCellDataStoring, into receiverCellData: MXKRoomBubbleCellDataStoring) -> Bool {
+        return false
+    }
     
     func applySelectedStyleIfNeeded(toCell cell: MXKRoomBubbleTableViewCell, cellData: RoomBubbleCellData) {
         

Riot/Modules/Room/TimelineCells/Styles/Plain/PlainRoomTimelineStyle.swift

@@ -49,6 +49,10 @@ class PlainRoomTimelineStyle: RoomTimelineStyle {
     func canAddEvent(_ event: MXEvent, and roomState: MXRoomState, to cellData: MXKRoomBubbleCellData) -> Bool {
         return true
     }
+
+    func canMerge(cellData: MXKRoomBubbleCellDataStoring, into receiverCellData: MXKRoomBubbleCellDataStoring) -> Bool {
+        return true
+    }
     
     func applySelectedStyleIfNeeded(toCell cell: MXKRoomBubbleTableViewCell, cellData: RoomBubbleCellData) {
         

Riot/Modules/Room/TimelineCells/Styles/RoomTimelineStyle.swift

@@ -39,7 +39,10 @@ protocol RoomTimelineStyle: Themable {
     
     /// Indicate to merge or not event in timeline
     func canAddEvent(_ event: MXEvent, and roomState: MXRoomState, to cellData: MXKRoomBubbleCellData) -> Bool
-    
+
+    /// Indicate to merge or not the `cellData` into `receiverCellData`
+    func canMerge(cellData: MXKRoomBubbleCellDataStoring, into receiverCellData: MXKRoomBubbleCellDataStoring) -> Bool
+
     /// Apply selected or blurred style on cell
     func applySelectedStyleIfNeeded(toCell cell: MXKRoomBubbleTableViewCell, cellData: RoomBubbleCellData)
 }