Unlike the increase function delta doesn't check for resets
and can go negative. This is similar to the prometheus delta
function.

IE11 fix for legend tables below graph

Add only display date option to table panel column

[skip ci]

[skip ci]

mysql graphical query builder

Explore: repair logging after recent Explore restructuring

this is a fix-up PR that cleans up Explore Logging after the recent
restructuring.

- log results need to be merged since query transactions have been
  introduced
- logging DS has its own language provider, query field, and start page
  (some of them based on prometheus components)
- added loader animation to log viewer
- removed logging logic from prometheus components

Explore: Pluggable components from datasource plugins

JS tooling: run TS grunt tasks only when files changed

* Add new build info metrics that contains more info

The goal was to add more information about Grafana. But rather than
just adding those to the current metrics I created a new metric
since its a common pattern in the prometheus community to expose that
info in a metric named `*_build_info`.

We keep the old metric to avoid introducing any breaking changes but
we should be able to remove it the next breaking change

- using grunt-newer to prefix precommit tasks
- only got it to work for tslint and tsc

Not applied to:

- sasslint does not take the file arguments in a way that grunt-newer
  recognizes
- no-only-tests throws an error when used with `newer`, but it's
  sub-second runtime

Updated grafana_stats.json

Explore: fix copy/paste on table cells

When selecting text via mouse, our ReactTable cells' click handler
triggers an event.

- check event target to be the link, only then handle the event

- when instantiating a datasource, the datasource service checks if the
  plugin module exports Explore components, and if so, attaches them to
  the datasource
- Explore component makes all major internal pluggable from a datasource
  `exploreComponents` property
- Moved Prometheus query field to promehteus datasource and registered
  it as an exported Explore component
- Added new Start page for Explore, also exported from the datasource

Explore: error handling and time fixes

Revert to sync loading of css, sometimes js loaded before css which c…

build: adds branch info to binary build

Makefile: dependency-driven target to build node_modules