Various fixes to problems discovered by 1000_pairs test and more

[Fix] query updating hive_posts.active no longer stops update on older active (which can come from edit) - fixes second set of problems with active value in 1000_pairs test

[Fix] delete_hive_post now properly updates active value - fixes first set of problems with it in 1000_pairs test

[Fix] order of posts in database_api.find_comments is now defined by order requested in call parameters (1000_pairs test)

[Fix] added escaping to find_comments values (escape_chars test)

[Fix] unified checks in various community related calls (in some cases it means there is check where there was none)

added find_community_id SQL function that follows other find_ routines (there is more places where it should be used, community related get_ranked_posts versions in particular)

hive/db/sql_scripts/hive_post_operations.sql

@@ -144,12 +144,13 @@ END
 $function$
 ;
 
-DROP FUNCTION if exists delete_hive_post(character varying,character varying,character varying, integer)
+DROP FUNCTION if exists delete_hive_post(character varying,character varying,character varying, integer, timestamp)
 ;
 CREATE OR REPLACE FUNCTION delete_hive_post(
   in _author hive_accounts.name%TYPE,
   in _permlink hive_permlink_data.permlink%TYPE,
-  in _block_num hive_blocks.num%TYPE)
+  in _block_num hive_blocks.num%TYPE,
+  in _date hive_posts.active%TYPE)
 RETURNS TABLE (id hive_posts.id%TYPE, depth hive_posts.depth%TYPE)
 LANGUAGE plpgsql
 AS
@@ -165,6 +166,7 @@ BEGIN
       WHERE ha.name = _author AND hpd.permlink = _permlink
     )
     , block_num = _block_num
+    , active = _date
   FROM hive_posts hp1
   INNER JOIN hive_accounts ha ON hp1.author_id = ha.id
   INNER JOIN hive_permlink_data hpd ON hp1.permlink_id = hpd.id