store teaserPid in topic

-update teaser pid as necessary in addPostToTopic, removePostFromTopic,
post purge
-removed 20x db calls from getTeasers
-fixed scroll to post in sub folder install
-upgrade script to update topics with teaserPid

src/posts/delete.js

@@ -167,6 +167,9 @@ module.exports = function(Posts) {
 						function (next) {
 							topics.decreasePostCount(postData.tid, next);
 						},
+						function(next) {
+							topics.updateTeaser(postData.tid, next);
+						},
 						function(next) {
 							user.incrementUserPostCountBy(postData.uid, -1, next);
 						},