Repair and clean-up Trac database

[matze]

During #2586, we've discovered that our trac database records are not consistent. It seems like there are some minor discrepancies, e.g.:

mysql> select count(sid), name from session_attribute where name in ("name", "password", "email") group by name;
+------------+--------------------------+
| count(sid) | name                     |
+------------+--------------------------+
|      40475 | email                    |
|      40175 | name                     |
|      40474 | password                 |
+------------+--------------------------+
5 rows in set (4.23 sec)                                                        

One would expect the count to be equal here. While this can probably be explained with some network issues and bugs over the years and may not require an in-depth investigation, but we should try to fix the records, at least.

[matze]

After #2586, cleanup was quite easy. All accounts now have both a email and a password:

mysql> select count(sid), name from session_attribute where authenticated=1 and name in ("name", "email", "password") group by name;
+------------+----------+
| count(sid) | name     |
+------------+----------+
|       5702 | email    |
|       5425 | name     |
|       5702 | password |
+------------+----------+

Not every one has a name though.