Fix case of function language for PostgreSQL 9.2+

Language names are case-sensitive in PostgreSQL 9.2+

Old upgrade packages have the wrong case, so upgrades on PG9.2+ require some gymnastics. First create a new language:

```sql
INSERT INTO pg_catalog.pg_language (
    lanname, lanowner, lanispl, lanpltrusted,
    lanplcallfoid, laninline, lanvalidator
) VALUES ('SQL', 10, false, true, 0, 0, 2248);
```

Next upgrade the database using the updater tool. Then re-create all functions that depend on the SQL language, but replace "LANGUAGE 'SQL'" with "LANGUAGE 'sql'". You can find them with this query:

```sql
SELECT pg_proc.proname, lanname
FROM pg_catalog.pg_proc
    JOIN pg_catalog.pg_language
        ON pg_proc.prolang = pg_language.oid
WHERE lanname = 'SQL';
```

Finally, when there are no more functions that depend on the 'SQL' language you can delete it:

```sql
DELETE FROM pg_catalog.pg_language
WHERE lanname = 'SQL';
```