Allow `onClick` on `next/link` child. This should not be a breaking change, but it's a very useful feature. Real-life use cases include: analytics or closing menu on navigation, and other.

- [x] allow optional `onClick` on `next/link` component's child
- [x] call original `child.props.onClick(e)` before `this.linkClicked(e)`
- [x] add integration tests
- [x] cancel the navigation if `e.defaultPrevented === true`

Fixes #1490

`idead` to `idea`

Just in case #3345 was a regression and nextjs should still support non webpack node envs for testing.

This accepts arguments to a node --inspect flag as well as other debugging node flags.

Resolves #4151 

This PR adds events for when there is a hash-only change in the URL. This is needed because `window.addEventListener('hashchange', ...)` does not work with next.js because it is using pushState.

I stumbled into this Issue https://github.com/zeit/next.js/issues/2868 and thought it should be mentioned properly in the documentation.

This fixes the generated page chunk created by the webpack `pages-plugin` which adds a new line in the beginning of the template, when using `output.libraryTarget` set to be [`umd`](https://webpack.js.org/configuration/output/#module-definition-systems) it returns the module.

Consider the following example, which is the output with the previous implementation:

```js
(function webpackUniversalModuleDefinition(root, factory) {
  if(typeof exports === 'object' && typeof module === 'object')
    module.exports = factory();
  else if(typeof define === 'function' && define.amd)
    define([], factory);
  else if(typeof exports === 'object')
    exports["MyLibrary"] = factory();
  else
    root["MyLibrary"] = factory();
})(typeof self !== 'undefined' ? self : this, function() {
  return
    __NEXT_REGISTER_PAGE(...)
});
```

`__NEXT_REGISTER_PAGE()` won't be executed since a `return` statement followed by a new line is the same as having a semicolon inserted right after the `return`. By removing the new line in the beginning of the source concatenation (which I suppose was added for stylistic reasons) this works as expected.

This example app shows you how to set up sitemap.xml and robots.txt files for proper indexing by search engine bots.

* Update typescript examples to use 1.0.1 of next-typescript

* Add .babelrc modifications to upgraded typescript examples

* Port Babel logic to new custom babel-loader for config injection.

* Update logic to also support babel.config.js configs.

* Add test for .babelrc

* Make inconsistent test work

This resolves the

> .value is not a valid Plugin property

error showing up for people in https://github.com/zeit/next.js/issues/4227

cc @timneutkens 

* Don’t use chunkhash in development

* Add test for dynamic imports styling

* Remove pre-load of dynamic page

* Make sure the browser gets closed only once

Restructure with-material-ui (patch)

Fixes #4442

Changes
* Update dependencies.
* Remove sending client prop to component on pages.
* Use withApollo correctly on components.
* Use `client.cache.reset()` instead of `prop.client.resetStore()`.

@adamsoffer @timneutkens 

* with-firebase-hosting: update next.js 6, readme about customization

* now next.js 6 is on Babel 7, remove conflicting babel deps
* update Next Server/Cloud Function .babelrc config
* update other deps: Cloud Functions to 1.x.x etc
* rm install-deps script as it is no longer used on deployment (firebase does not upload node_modules)
* make scripts consistent in their wrapping of dirs with \" (escaped double quotes)

* with-firebase-hosting: pin next to "latest" version

* with-firebase-hosting: fix lint errors

Adds an example based off of @jthegedus work on firebase hosting, compatible with next v6 and using typescript in both the firebase functions and the next app.

* set cache-control public

* test for Cache-Control header

* set Cache-Control header for commons/main.js

* Fix example with-componentdidcatch

* Improve demo in example
: with-componentdidcatch

* Change next dependency to latest

* Revert _app.js

* Added license to package.json.
* Modified package name same as dir name.

* This is minor refactoring.
* Apply alphabetical order to files list.

* fix: fixing issue with ios10 and webpack uglify es httebpack-plugin/issues/92

* chore: formatting

* chore: formatting

Use `withRouter` HOC to avoid _deprecation warning_ using `url`