moved mentions into a separate component - MentionLine, added collapsing

of mentions when there's too many of 'em

src/components/mention_link/mention_link.scss

@@ -40,6 +40,10 @@
   .new {
     margin-right: 0.25em;
 
+    &.-firstMention {
+      display: none;
+    }
+
     &.-you {
       & .shortName,
       & .full {
@@ -115,12 +119,6 @@
     }
   }
 
-  &:not(.-oldPlace) {
-    .new.-firstMention {
-      display: none;
-    }
-  }
-
   &:hover .new .full {
     opacity: 1;
     pointer-events: initial;

src/components/mention_link/mention_link.vue

@@ -23,7 +23,8 @@
         @click.prevent="onClick"
       >
         <!-- eslint-disable vue/no-v-html -->
-        <span class="shortName"><span class="userName" v-html="userName" /></span><span class="you" v-if="isYou">{{ $t('status.you')}}</span>
+        <span class="shortName"><span class="userName" v-html="userName" /></span>
+        <span class="you" v-if="isYou">{{ $t('status.you') }}</span>
         <!-- eslint-enable vue/no-v-html -->
       </button>
       <span