Minor timeline UX improvements.

src/utils/media-to-view.ts

@@ -200,16 +200,15 @@ export const findClosestMediaIndex = (
       }
     | undefined;
 
-  for (let i = 0; i < mediaArray.length; ++i) {
-    const media = mediaArray[i];
-    const start = media.getStartTime();
-    const end = media.getEndTime();
-    if (!cameraIDs.has(media.getCameraID()) || !start || !end) {
+  for (const [i, media] of mediaArray.entries()) {
+    if (!cameraIDs.has(media.getCameraID())) {
       continue;
     }
 
-    if (start <= targetTime && end >= targetTime) {
-      if (!refPoint) {
+    if (media.includesTime(targetTime)) {
+      const start = media.getStartTime();
+      const end = media.getEndTime();
+       if (!refPoint || !start || !end) {
         return i;
       }
       const delta =

src/utils/timeline-source.ts

@@ -3,7 +3,7 @@ import add from 'date-fns/add';
 import sub from 'date-fns/sub';
 import { DataSet } from 'vis-data';
 import { IdType, TimelineItem, TimelineWindow } from 'vis-timeline/esnext';
-import { CameraConfig, ClipsOrSnapshotsOrAll, RecordingSegment } from '../types';
+import { ClipsOrSnapshotsOrAll, RecordingSegment } from '../types';
 import { CameraManager } from '../camera/manager';
 import { EventQuery } from '../camera/types';
 import { capEndDate, convertRangeToCacheFriendlyTimes } from '../camera/util';