Fixes: https://tickets.smeder.ee/~jan0sch/smederee/tickets/6

- enable Xfatal-warnings flag for each module that doesn't use twirl
- fix a fatal warning in the `MarkdownRenderer`

This release contains BREAKING CHANGES in the database structure!

To mitigate the effect create a backup of your database first. Then follow
these instructions:

1. stop the service
2. dump the data of your database only (`pg_dump -a dbname > data.sql`)
3. !!! Remove the `flyway_schema_history` tables from the dump !!!
4. drop the database and create a new one with the same name
5. apply the update
6. start the service
7. stop the service after the migrations have been applied
8. restore the data (`cat data.sql | psql dbname`)

Please note that you might need additional parameters for `pg_dump` and `psql`
depending on your database configuration like username, password or prepended
`sudo` command.

Changed
-------

- **BREAKING CHANGE** remove unnecessary quoting in sql

Remove unnecessary quoting in sql commands and migrations. It gives no benefit
because we do not use reserved names and it increases the amount of characters
to type.

BREAKING CHANGE!
----------------

This will break already running systems!

To mitigate the effect create a backup of your database first. Then follow
these instructions:

1. stop the service
2. dump the data of your database only (`pg_dump -a dbname > data.sql`)
3. !!! remove the flyway_schema_history tables from the dump !!!
4. drop the database and create a new one with the same name
5. apply the update
6. start the service
7. stop the service after the migrations have been applied
8. restore the data (`cat data.sql | psql dbname`)

Please note that you might need additional parameters for pg_dump and psql
depending on your database configuration like username, password or prepended
sudo command.