Allow videos in posts, simplify post image view

CHDataManagement/Page Elements/ContentElements/PostVideo.swift

@@ -0,0 +1,14 @@
+
+struct PostVideo: HtmlProducer {
+
+    let videos: [FileResource]
+
+    func populate(_ result: inout String) {
+        result += "<video autoplay loop muted>"
+        result += "Video not supported."
+        for video in videos {
+            result += "<source src='\(video.absoluteUrl)' type='\(video.type.htmlType!)'>"
+        }
+        result += "</video>"
+    }
+}