* support panel repeat for datasource template variable

* support All option

This seems to work for the three use cases:

- Overflow on the left
- Overflow on the right
- Elements that are out of view on page load

* use utf8mb4 character set for connections to mysql

* use utf8mb4 character set for tables, shorten varchar fields used in unique indexes

* migration type to update table character set

* update table character sets

* set charset for temp_user.status

* gofmt

Fix some spelling/grammar/wording problems in What's New in Grafana v4.0

ref #7469

Update README.md

Adds the Delete function to the Session wrapper so that the Macaron
function for deleting keys from a Session can be used.

https://go-macaron.com/docs/middlewares/session#implement-provider-interface

Add common type for oauth authorization errors

In systemd `After=` merely codes an ordering relation and does not start
other units.

Grafana needs to specify that it wants to start up _after_ either of the
supported DB services have started, _if they start_.

Enabling the database services, however, is out of scope for Grafana.

We now obtain credentials based on the container task's role
rather than just relying on the credentials of the enclosing
container instance.

Fixes #6700.