PollListItem freed from noticeListItemAdapter clutches

In the future, use events for formatting microapp notices, more specifically
through the plugin's function "showNoticeContent" or similar, which is called
from MicroAppPlugin, which is extended from ActivityHandlerPlugin.
Minor cosmetic changes to form_settings. Hope they're right.
Adding event StartShowNoticeItemNotice with corresponding End

Runs just before outputting the "top" part of a NoticeListItem to HTML
so plugins can jump in and do their thing.
BookmarkListItem removed in favor of event-driven rendering
Updating TwitterBridge README to be clearer on installation
Show poll results also to non-logged in visitors
Making some autumn cleaning in the themes
EventPlugin now uses event handling instead of NLI adapter
Add "Date" header to mail, some clients require this to show corrent message receiving time.
Conversation link as default, permalink for /notice
Notice_source checks in better code style
Show permalinks only for local notices

the "from [site]" already links to the permalink
UPGRADE file fixed, forgot to mention PHP modules

php5-gmp is an added requirement from StatusNet 1.1.1,
our BigInteger library doesn't seem to work well without it
and bcmath was unavailable at least in Debian testing repo.
Diaspora public key published in WebFinger
We're using URLMapper, not Net_URL_Mapper
DirectMessage moved into a plugin, not done yet

We still have to move some API calls into the new plugin.
Simulation does not support plugins yet
DirectMessage API functions moved to plugin
UserActivityStream export of DMs moved to plugin
&$supported in CommandSupportedAPI event is boolean

not array as we specified here