Explore: Make sure line graphs get different colors

Improved error handling when rendering dashboard panels

Optionally set histogram x-axis min/max

New Bar Gauge panel

Moved delete button in Dashboard settings

Cleaned out some sass variables

Alpha react-virtualized table

Heatmap: fix for negative values

Fixed more typescript no implicit any issues

Heatmap fixes and improvements

Removed SASS variables being used in JS

Also push to ci metrics to new shared HM instance

* grafana/master:
  Fixed type issues introduced by adding angular types
  Typescript noAny fixes, start of a long journey
  Updated code stats collection
  Updated path to new script
  POC on collecting metrics in ci process
  renamed default variables: s -> sm, m -> md, l -> lg
  removed gf-form-margin variable and replaced with space- variables where it was used
  heatmap: able to hide buckets with zero value #12080
  s -> sm, m -> md, l -> lg
  heatmap: fix prometheus buckets sorting, closes #15637
  s -> sm, m -> md, l -> lg
  removed headings-margin-bottom variable
  remove kbn test
  Added scopedVars argument in datasourceSrv.get in DataPanel
  Refactoring of multi-value datasource PR #15812
  fixed minor misstake with dashboard padding
  removed -margin, replaced with new general variables
  added new space variables to margins in AddPanelWidget, add_data_source, dashboard_settings and sidemenu
  added new variables for spacing, set margins in _cards with new variables
  Make datasource variables multiselect and dashboard repeatable

Progress on fixing typescript noImplicitAny issues 

Renamed default.ts variables

Removed headings-margin-bottom and gf-form-margin

Removed variable $panel-margin

Collecting metrics in ci process