update design of editor to look as close to original tile (and design)

the buttons below the composer are overlayed onto the previous event.
In case of the last event, for now we make them not overflow, but make the
tile grow. The design says it should overlay on the main composer for the last
event tile, postponing that for a bit though as not sure what is the best way
to do that.

res/css/views/elements/_MessageEditor.scss

@@ -16,14 +16,14 @@ limitations under the License.
 
 .mx_MessageEditor {
     border-radius: 4px;
-    background-color: $header-panel-bg-color;
-    padding: 11px 13px 7px 56px;
+    padding: 3px;
+    margin: -7px -7px -5px -7px; // no idea why this is working
 
     .mx_MessageEditor_editor {
         border-radius: 4px;
         border: solid 1px #e9edf1;
         background-color: #ffffff;
-        padding: 10px;
+        padding: 3px;
         white-space: pre-wrap;
         word-wrap: break-word;
         outline: none;
@@ -49,7 +49,14 @@ limitations under the License.
         display: flex;
         flex-direction: row;
         justify-content: end;
-        padding: 5px 0;
+        padding: 5px;
+        position: absolute;
+        left: 0;
+        background: $header-panel-bg-color;
+        z-index: 100;
+        right: 0;
+        margin: 0 -110px 0 0;
+        padding-right: 108px;
 
         .mx_AccessibleButton {
             margin-left: 5px;
@@ -62,3 +69,7 @@ limitations under the License.
         height: 0;
     }
 }
+
+.mx_EventTile_last .mx_MessageEditor_buttons {
+    position: static;
+}

res/css/views/rooms/_EventTile.scss

@@ -43,6 +43,10 @@ limitations under the License.
     padding-top: 0px ! important;
 }
 
+.mx_EventTile_isEditing {
+    background-color: $header-panel-bg-color;
+}
+
 .mx_EventTile .mx_SenderProfile {
     color: $primary-fg-color;
     font-size: 14px;

src/components/views/rooms/EventTile.js

@@ -540,6 +540,7 @@ module.exports = withMatrixClient(React.createClass({
 
         const classes = classNames({
             mx_EventTile: true,
+            mx_EventTile_isEditing: this.props.isEditing,
             mx_EventTile_info: isInfoMessage,
             mx_EventTile_12hr: this.props.isTwelveHour,
             mx_EventTile_encrypting: this.props.eventSendStatus === 'encrypting',