[ticket/14638] Rollback changes from 3.2.x version
Mistakenly brought in the modified 3.2.x version verbatim instead of diffing
against the 3.1.x version of ucp_main.php. Removed any changes I didn't
explicitly make.
[ticket/14638] New UCP hooks for subscriptions
Adds various event hooks to the Manage subscriptions page of the User
Control Panel. core.ucp_subscribed_post_data allows us to handle
additional post data from the form that unwatches subscriptions.
core.ucp_main_subscribed_forums_modify_query,
core.ucp_main_topiclist_count_modify_query and
core.ucp_main_topiclist_modify_query all modify the queries used to get
the list of subscribed forums and subscribed/bookmarked topics.
core.ucp_main_subscribed_forum_modify_template_vars and
core.ucp_main_topiclist_topic_modify_template_vars modify the template
variable array associated with each subscribed forum and topic row.
This is a backport to 3.1.x of the code in PR #4318.
