fix: cleanup dist folder, change README

- move images for README into docs/img
- move libs/* into utils. libs folder is copied into dist by grafana-toolkit
- remove d3-scale-chromatic sources, use it from dependencies
- update compatible versions in README
- update installation info

src/util/d3/d3-scale-chromatic.ts

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+import * as d3 from 'd3';
+import * as d3ScaleChromaticOrig from 'd3-scale-chromatic';
+
+// Add GnYlRd color schema to d3-scale-chromatic
+
+let GnYlRdScheme = new Array(3)
+  .concat(
+    '91cf60ffffbffc8d59',
+    '1a9641a6d96afdae61d7191c',
+    '1a9641a6d96affffbffdae61d7191c',
+    '1a985091cf60d9ef8bfee08bfc8d59d73027',
+    '1a985091cf60d9ef8bffffbffee08bfc8d59d73027',
+    '1a985066bd63a6d96ad9ef8bfee08bfdae61f46d43d73027',
+    '1a985066bd63a6d96ad9ef8bffffbffee08bfdae61f46d43d73027',
+    '0068371a985066bd63a6d96ad9ef8bfee08bfdae61f46d43d73027a50026',
+    '0068371a985066bd63a6d96ad9ef8bffffbffee08bfdae61f46d43d73027a50026'
+  )
+  .map(function(specifier) {
+    var n = (specifier.length / 6) | 0,
+      colors = new Array(n),
+      i = 0;
+    while (i < n) {
+      colors[i] = '#' + specifier.slice(i * 6, ++i * 6);
+    }
+    return colors;
+  });
+
+let GnYlRd = d3.interpolateRgbBasis(GnYlRdScheme[GnYlRdScheme.length - 1]);
+
+let d3ScaleChromatic = {
+  ...d3ScaleChromaticOrig,
+  interpolateGnYlRd: GnYlRd,
+};
+
+export { d3ScaleChromatic };

src/util/grafana/events/appEvents.ts

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+export interface AppEvent<T> {
+  readonly name: string;
+  payload?: T;
+}

src/util/grafana/events/events.ts

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+import { AppEvent } from './appEvents';
+
+export interface GraphHoverPayload {
+  pos: any;
+  panel: {
+    id: number;
+  };
+}
+
+export var graphHover: AppEvent<GraphHoverPayload> | string = { name: 'graph-hover' };
+export var graphHoverClear: AppEvent<any> | string = { name: 'graph-hover-clear' };
+
+export function fallbackToStringEvents() {
+  graphHover = 'graph-hover';
+  graphHoverClear = 'graph-hover-clear';
+}

src/util/grafana/events/index.ts

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+import * as CoreEvents from './events';
+import * as PanelEvents from './panelEvents';
+export { CoreEvents, PanelEvents };

src/util/grafana/events/panelEvents.ts

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+import { AppEvent } from './appEvents';
+
+export interface DataQueryError {
+  data?: {
+    message?: string;
+    error?: string;
+  };
+  message?: string;
+  status?: string;
+  statusText?: string;
+  refId?: string;
+  cancelled?: boolean;
+}
+
+export var refresh: AppEvent<undefined> | string = { name: 'refresh' };
+export var render: AppEvent<any> | string = { name: 'render' };
+export var dataError: AppEvent<DataQueryError> | string = { name: 'data-error' };
+export var dataReceived: AppEvent<any[]> | string = { name: 'data-received' };
+export var dataSnapshotLoad: AppEvent<any[]> | string = { name: 'data-snapshot-load' };
+export var editModeInitialized: AppEvent<undefined> | string = { name: 'init-edit-mode' };
+
+export function fallbackToStringEvents() {
+  refresh = 'refresh';
+  render = 'render';
+  dataError = 'data-error';
+  dataReceived = 'data-received';
+  dataSnapshotLoad = 'data-snapshot-load';
+  editModeInitialized = 'init-edit-mode';
+}

src/util/polygrafill/README.md

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+1. @grafana/data is not supported in grafana 5.x and 6.2. The workaround is
+the module `./util/grafana/events` that include copy-pasted events
+from @grafana/data and app/core from grafana sources.
+
+2. Newly Grafana versions flood Console with
+"Usage strings as events is deprecated ..." messages.
+This module has a function to detect if Grafana’s Emitter support AppEvent style event ids.
+

src/util/polygrafill/funcs.ts

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+import { Emitter } from 'grafana/app/core/utils/emitter';
+
+// Old Grafana releases use strings as event ids and
+// new event ids in form of object {name: "event-id"} are not
+// supported properly: first defined listener will receive
+// all emitted events despite of the value in 'name' field.
+//
+// This method detects this behaviour and return true
+// only for new Grafana versions.
+export function hasAppEventCompatibleEmitter(emitter: Emitter): boolean {
+  // Grafana 7.4 has new event bus for Angular plugins. It is has a 'subscribe' method.
+  let emitterProto = Object.getPrototypeOf(emitter);
+  if (Object.prototype.hasOwnProperty.call(emitterProto, 'subscribe')) {
+    return true;
+  }
+
+  let receiveEvents = 0;
+  let eventId: any = { name: 'non-existed-event-id' };
+  let eventId2: any = { name: 'non-existed-event-id-2' };
+  emitter.on(eventId, function() {
+    receiveEvents++;
+  });
+  emitter.emit(eventId);
+  emitter.emit(eventId2);
+  emitter.removeAllListeners(eventId);
+
+  // New Grafana versions should receive one event.
+  return receiveEvents === 1;
+}

src/util/polygrafill/index.ts

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+import * as Polygrafill from './funcs';
+export { Polygrafill };