Use base classes for message types

This avoids unnecessary duplication of code for "avatar", "sender" etc in the general layout of messages.

src/components/messages/MessageOutgoing.vue

@@ -0,0 +1,40 @@
+<template>
+  <!-- BASE CLASS FOR OUTGOING MESSAGE -->
+  <div class="messageOut">
+    <div class="op-button" ref="opbutton">
+      <v-btn icon @click.stop="showContextMenu($refs.opbutton)"
+        ><v-icon>more_vert</v-icon></v-btn
+      >
+    </div>
+    <QuickReactions :event="event" :reactions="reactions" />
+    <!-- SLOT FOR CONTENT -->
+    <slot></slot>
+    <v-avatar
+      class="avatar"
+      size="32"
+      color="#ededed"
+      @click.stop="ownAvatarClicked"
+    >
+      <img v-if="userAvatar" :src="userAvatar" />
+      <span v-else class="white--text headline">{{ userAvatarLetter }}</span>
+    </v-avatar>
+    <!-- <div class="sender">{{ "You" }}</div> -->
+    <div class="senderAndTime">
+      <div class="time">
+        {{ formatTime(event.event.origin_server_ts) }}
+      </div>
+      <div class="status">{{ event.status }}</div>
+    </div>
+  </div>
+</template>
+
+<script>
+import messageMixin from "./messageMixin";
+
+export default {
+  mixins: [messageMixin],
+};
+</script>
+<style lang="scss">
+@import "@/assets/css/chat.scss";
+</style>