changes in various places to clean the code and fix small problems

[Fix] wrapping of internal routines in @return_error_info etc is superfluous

[Fix] reputation used for marking with reputation-0/1 should be the logarithmic one, not raw

[Cleanup] is_muted is always present in bridge compatible posts - removed superfluous check

[Cleanup] removed no longer used parameter of append_statistics_to_post

[Fix] observer is now actually passed to SQL in all cases that fall under _get_ranked_posts_for_all

[Cleanup] added bridge_api_post_discussion type (extension to bridge_api_post) and used it in get_discussion (changed to match different order and data of result)

[Fix] supplemented is_muted to bridge_api_post_reblogs type and SQL function that used it: bridge_get_by_feed_with_reblog