Add typedefs for EuiAvatar component and color service (#1120)

This PR adds typedefs for the following:
- `EuiAvatar` component
- `color` service

src/components/avatar/index.d.ts

@@ -0,0 +1,25 @@
+/// <reference path="../common.d.ts" />
+
+import { HTMLAttributes, SFC } from 'react';
+
+declare module '@elastic/eui' {
+
+  export type AvatarSize = 's' | 'm' | 'l' | 'xl';
+
+  export type AvatarType = 'user' | 'space';
+
+  export interface EuiAvatarProps {
+    name: string;
+    color?: string;
+    initials?: string;
+    initialsLength?: number;
+    className?: string;
+    imageUrl?: string;
+    size?: AvatarSize;
+    type?: AvatarType;
+  }
+
+  export const EuiAvatar: SFC<
+    CommonProps & HTMLAttributes<HTMLDivElement> & EuiAvatarProps
+    >;
+}

src/components/form/field_search/index.d.ts

@@ -17,6 +17,7 @@ declare module '@elastic/eui' {
     isInvalid?: boolean;
     fullWidth?: boolean;
     isLoading?: boolean;
+    incremental?: boolean;
   }
 
   export const EuiFieldSearch: SFC<

src/components/index.d.ts

@@ -1,4 +1,5 @@
 /// <reference path="./common.d.ts" />
+/// <reference path="./avatar/index.d.ts" />
 /// <reference path="./button/index.d.ts" />
 /// <reference path="./context_menu/index.d.ts" />
 /// <reference path="./flex/index.d.ts" />

src/services/color/index.d.ts

@@ -0,0 +1,16 @@
+
+declare module '@elastic/eui' {
+  export const VISUALIZATION_COLORS: string[];
+
+  export const DEFAULT_VISUALIZATION_COLOR: string;
+
+  type rgbDef = [number, number, number];
+
+  export const hexToRbg: (hex: string) => rgbDef;
+  export const rgbToHex: (rgb: string) => string;
+
+  export const isColorDark: (red: number, green: number, blue: number) => boolean;
+
+  export const calculateLuminance: (red: number, green: number, blue: number) => number;
+  export const calculateContrast: (rgb1: rgbDef, rgb2: rgbDef) => number;
+}

src/services/index.d.ts

@@ -1,3 +1,4 @@
 /// <reference path="./alignment.d.ts" />
 /// <reference path="./key_codes.d.ts" />
+/// <reference path="./color/index.d.ts" />
 /// <reference path="./popover/index.d.ts" />