tech: migrates to none deprecated mail lib

Support IPv6 in Auth proxy white list

Default value for uploading images in alert notifiers

Clarified formatting multiple values doc

alert: fixes broken link back to grafana

dashboard: allow alerts to be saved for new/provisioned dashboards

when we made image upload optional we didnt
show the default value properly in the UI. Which
caused confusing. This commit apply the default
values to existing notifiers in the edit pages
and reverts back to using uploadimage=true as the
default value.

This changes the logic for the alert validation in the extractor. Validation
is executed twice, once before attempting to save the alerts and once after
saving the dashboard while saving the alerts to the db. The first validation
will not require that the alert has a dashboard id which allows new dashboards
with alerts to be saved.

Fixes #11247

closes #11095

gomail is missing a maintainer so we are
switching to an active fork

ref https://github.com/go-gomail/gomail/issues/108

closes #7189

cloes #11054

If Grafana was configured to use a subpath it
was included twice in the link from the
alert notification back to Grafana.

closes #11403

Make the value to text mapping more similar to singlestat solution.
Adds more tests.
Also, allows string to be mapped to other string besides numeric values.

provisioning: removes id from dashboard.json

[skip ci]

Add hints for the 'pd' Duplicate Panel command from PR #11264

Add new currency - Czech koruna

Currency used in Czech republic.

if dashboard json files contains `id` we
will just remove it form the dashboard model
before importing it into the database.

closes #11138

- Add some tests
- Make error message more helpful

doc: add missing word to graphite docs

dataproxy: adds dashboardid and panelid as tags

[skip ci]

fixes #8358

Postgres, MySQL, MSSQL minor refactoring/unification

Make golint happier

Alerting: Add retry mechanism

added media breakpoint to legend-right