chore: upgrade 'babel' to version 7, 'ava' to version 1, 'react' and other modules

- change `prop-types` dependency as suggested by Dan Abramov
[here](facebook/prop-types#44). Fixes #110.
- upgrade babel to version 7 by using [babel-upgrade](https://github.com/babel/babel-upgrade).
- upgrade ava to version 1 and adjust the configuration.
- update `ava` test snapshots to version 2.
- rework the test scripts to have: "test:ci", "test" and "watch:test".
- install [esm](https://github.com/standard-things/esm) to load ES6 modules in
`ava` tests.
- upgrade `eslint` and other modules excluding `flag-icon-css` to the latest versions.
- pin `postcss-custom-properties` to version 7 because the next version is async
and `css-modules-require-hook`only supports sync modules.
- update lock files.

test: add 'test.js' extension to test files

chore: bump 'flag-icon-css' to '3.2.1', tweak 'prebuild' scripts

docs: add reference to 'TypeScript' definitions for this module

chore: run 'flow-typed update' and exclude 'react-test-renderer' (errors, needs work)

Author: matteocng

.babelrc

@@ -1,28 +1,40 @@
 {
 	"presets": [
-		"react"
+		"@babel/preset-react",
+		"@babel/preset-flow"
 	],
 	"plugins": [
-		"transform-object-rest-spread",
-		"transform-export-extensions"
+		"@babel/plugin-proposal-object-rest-spread",
+		"@babel/plugin-proposal-export-default-from",
+		"@babel/plugin-proposal-export-namespace-from"
 	],
 	"comments": false,
 	"env": {
 		"build": {
-			"presets": ["es2015"],
-			"ignore": ["**/__tests__/"]
+			"presets": [
+				"@babel/preset-env"
+			],
+			"ignore": [
+				"**/__tests__/"
+			]
 		},
 		"module": {
 			"presets": [
-				["es2015", {
-					"modules": false
-				}]
+				[
+					"@babel/preset-env",
+					{
+						"modules": false
+					}
+				]
 			],
-			"ignore": ["**/__tests__/"]
+			"ignore": [
+				"**/__tests__/"
+			]
 		},
 		"testing": {
-			"presets": ["es2015"],
-			"plugins": ["babel-plugin-istanbul"]
+			"plugins": [
+				"babel-plugin-istanbul"
+			]
 		}
 	}
 }

README.md

@@ -231,7 +231,11 @@ const FlagIcon = CustomFlagIconFactory(React, options)
 
 **Runtime type checking**: in development mode (`process.env.NODE_ENV !== 'production'`), when using unsupported props or prop values, you are warned at runtime by *Failed prop type* errors in the browser console. Feature powered by [`prop-types`](https://github.com/reactjs/prop-types).
 
-**Static type checking**: if you use Facebook's [`flow`](https://github.com/facebook/flow) in your app (otherwise you can skip this section, unless you want to submit a pull request), it should automatically pick up this package's definitions from the `.js.flow` files that are distributed with it, checking your code accordingly when you run `yarn flow`. Using the latest `Flow` version or the version in `./package.json` is recommended. We also recommend using a `Flow`-aware editor such as [`Nuclide`](https://nuclide.io/) for [`Atom`](https://atom.io/).
+**Static type checking**:
+
+If you use Facebook's [`flow`](https://github.com/facebook/flow) in your app (otherwise you can skip this section, unless you want to submit a pull request), it should automatically pick up this package's definitions from the `.js.flow` files that are distributed with it, checking your code accordingly when you run `yarn flow`. Using the latest `Flow` version or the version in `./package.json` is recommended. We also recommend using a `Flow`-aware editor such as [`Nuclide`](https://nuclide.io/) for [`Atom`](https://atom.io/).
+
+If you use Microsoft's [`TypeScript`](https://www.typescriptlang.org/) in your app (otherwise you can skip this section, unless you want to submit a pull request), the package that contains the type definitions for this module is: [@types/react-flag-icon-css](https://www.npmjs.com/package/@types/react-flag-icon-css).
 
 ## Contributing
 

flow-typed/npm/@babel/cli_vx.x.x.js

@@ -0,0 +1,87 @@
+// flow-typed signature: 1b3886eca11e35f7cf8fe31aa44c0d13
+// flow-typed version: <<STUB>>/@babel/cli_v^7.2.3/flow_v0.77.0
+
+/**
+ * This is an autogenerated libdef stub for:
+ *
+ *   '@babel/cli'
+ *
+ * Fill this stub out by replacing all the `any` types.
+ *
+ * Once filled out, we encourage you to share your work with the
+ * community by sending a pull request to:
+ * https://github.com/flowtype/flow-typed
+ */
+
+declare module '@babel/cli' {
+  declare module.exports: any;
+}
+
+/**
+ * We include stubs for each file inside this npm package in case you need to
+ * require those files directly. Feel free to delete any files that aren't
+ * needed.
+ */
+declare module '@babel/cli/bin/babel-external-helpers' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/bin/babel' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/lib/babel-external-helpers' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/lib/babel/dir' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/lib/babel/file' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/lib/babel/index' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/lib/babel/options' {
+  declare module.exports: any;
+}
+
+declare module '@babel/cli/lib/babel/util' {
+  declare module.exports: any;
+}
+
+// Filename aliases
+declare module '@babel/cli/bin/babel-external-helpers.js' {
+  declare module.exports: $Exports<'@babel/cli/bin/babel-external-helpers'>;
+}
+declare module '@babel/cli/bin/babel.js' {
+  declare module.exports: $Exports<'@babel/cli/bin/babel'>;
+}
+declare module '@babel/cli/index' {
+  declare module.exports: $Exports<'@babel/cli'>;
+}
+declare module '@babel/cli/index.js' {
+  declare module.exports: $Exports<'@babel/cli'>;
+}
+declare module '@babel/cli/lib/babel-external-helpers.js' {
+  declare module.exports: $Exports<'@babel/cli/lib/babel-external-helpers'>;
+}
+declare module '@babel/cli/lib/babel/dir.js' {
+  declare module.exports: $Exports<'@babel/cli/lib/babel/dir'>;
+}
+declare module '@babel/cli/lib/babel/file.js' {
+  declare module.exports: $Exports<'@babel/cli/lib/babel/file'>;
+}
+declare module '@babel/cli/lib/babel/index.js' {
+  declare module.exports: $Exports<'@babel/cli/lib/babel/index'>;
+}
+declare module '@babel/cli/lib/babel/options.js' {
+  declare module.exports: $Exports<'@babel/cli/lib/babel/options'>;
+}
+declare module '@babel/cli/lib/babel/util.js' {
+  declare module.exports: $Exports<'@babel/cli/lib/babel/util'>;
+}