Use Unicode aware character-wise slicing (#159)

src/app/organisms/room/RoomViewContent.jsx

@@ -356,7 +356,7 @@ function RoomViewContent({
       <button type="button" onClick={() => openProfileViewer(mEvent.sender.userId, roomId)}>
         <Avatar
           imageSrc={mEvent.sender.getAvatarUrl(initMatrix.matrixClient.baseUrl, 36, 36, 'crop')}
-          text={getUsernameOfRoomMember(mEvent.sender).slice(0, 1)}
+          text={getUsernameOfRoomMember(mEvent.sender)}
           bgColor={senderMXIDColor}
           size="small"
         />

src/app/organisms/room/RoomViewHeader.jsx

@@ -24,7 +24,7 @@ function RoomViewHeader({ roomId }) {
 
   return (
     <Header>
-      <Avatar imageSrc={avatarSrc} text={roomName.slice(0, 1)} bgColor={colorMXID(roomId)} size="small" />
+      <Avatar imageSrc={avatarSrc} text={roomName} bgColor={colorMXID(roomId)} size="small" />
       <TitleWrapper>
         <Text variant="h2">{roomName}</Text>
         { typeof roomTopic !== 'undefined' && <p title={roomTopic} className="text text-b3">{roomTopic}</p>}