Clean up MessageDelegate.

Include a generic component for text bubbles.
Fixes #11.

qml/component/StateBubble.qml

@@ -2,25 +2,10 @@ import QtQuick 2.9
 import QtQuick.Controls 2.2
 import QtQuick.Controls.Material 2.2
 
-Rectangle {
-    readonly property bool isEmote: eventType === "emote"
+TextDelegate {
+    maximumWidth: messageListView.width
+    highlighted: eventType === "emote"
+    timeLabelVisible: false
 
-    id: stateRect
-
-    width: Math.min(stateText.implicitWidth + 24, messageListView.width)
-    height: stateText.implicitHeight + 24
-
-    color: isEmote ? Material.accent : background
-
-    Label {
-        id: stateText
-        text: "<b>" + author.displayName + "</b> " + display
-        color: isEmote ? "white" : Material.foreground
-        linkColor: isEmote || darkTheme ? "white" : Material.accent
-        anchors.fill: parent
-        anchors.margins: 12
-        wrapMode: Label.Wrap
-        textFormat: Text.StyledText
-        onLinkActivated: Qt.openUrlExternally(link)
-    }
+    displayText: "<b>" + author.displayName + "</b> " + display
 }