Bidirectional twitter sync - and some small fixes

This pull request mainly contains the bidirectional twitter sync.

Additionally there are some smaller things:
* fromgplus: There is an additional detecting for posting loops (which is necessary for the alternate Google+ posting connector)
* The user agent in some addons had changed due to CloudFlare that blocked the old one
* pumpio: Support for a different kind of reshare look
* pumpio: avoiding some SQL warnings