Implement message sending. Refactor the timeline. Fix various UI/UX issues and add scroll to bottom timeline button.

ElementX/Sources/Services/Room/MockRoomProxy.swift

@@ -46,4 +46,8 @@ struct MockRoomProxy: RoomProxyProtocol {
     func displayNameForUserId(_ userId: String, completion: @escaping (Result<String?, RoomProxyError>) -> Void) {
         
     }
+    
+    func sendMessage(_ message: String, callback: ((Result<Void, RoomProxyError>) -> Void)?) {
+        
+    }
 }

ElementX/Sources/Services/Room/RoomProxy.swift

@@ -165,6 +165,25 @@ class RoomProxy: RoomProxyProtocol {
         }
     }
     
+    func sendMessage(_ message: String, callback: ((Result<Void, RoomProxyError>) -> Void)?) {
+        let messageContent = messageEventContentFromMarkdown(md: message)
+        let transactionId = genTransactionId()
+        
+        messageProcessingQueue.async {
+            do {
+                try self.room.send(msg: messageContent, txnId: transactionId)
+                
+                DispatchQueue.main.async {
+                    callback?(.success(()))
+                }
+            } catch {
+                DispatchQueue.main.async {
+                    callback?(.failure(.failedSendingMessage))
+                }
+            }
+        }
+    }
+    
     // MARK: - Private
     
     fileprivate func appendMessage(_ message: AnyMessage) {

ElementX/Sources/Services/Room/RoomProxyProtocol.swift

@@ -14,6 +14,7 @@ enum RoomProxyError: Error {
     case backwardStreamNotAvailable
     case failedRetrievingMemberAvatarURL
     case failedRetrievingMemberDisplayName
+    case failedSendingMessage
 }
 
 enum RoomProxyCallback {
@@ -43,5 +44,7 @@ protocol RoomProxyProtocol {
     
     func paginateBackwards(count: UInt, callback: ((Result<Void, RoomProxyError>) -> Void)?)
     
+    func sendMessage(_ message: String, callback: ((Result<Void, RoomProxyError>) -> Void)?)
+    
     var callbacks: PassthroughSubject<RoomProxyCallback, Never> { get }
 }