* Update the string that clears the console.

#1914
I've tested it with Windows 10 and 7, node versions from ~5.0.0 up to 7.7.0.
Didn't managed to test it on 8 but it should be fine.

* Update windows string

Add windows specific string for clearing the console.

* add support to set REACT_EDITOR to none

* change README message

* change condition to avoid problems with editor being null

* move condition to avoid extra code

* Update README.md with a note that reminds users to prepend REACT_APP_ to their environment variables. 
* Based on #865, where Dan Abramov suggests the person who filed the issue create a PR with these changes.
* Took the language from [Adding Custom Environment Variables](https://github.com/facebookincubator/create-react-app/tree/master/packages/react-scripts/template#adding-custom-environment-variables)

Fixes #2793

Adds support for the error overlay to detect and open the file with the error in MacVim.

Relates to #2636.

Add TypeScript to **Popular Alternatives**

* Fix path regex match bug

* Use the escape-string-regexp package to escape regex characters

* Remove redundant character escape from path

* Add removed escape of backslashes

Replace `provide a lot value` with `provide a lot of value`.

* use safer/more aesthetic syntax

* fix typo

The launch configuration code provided is not compatible with VSCode since version 1.19.
The proposed documentation change is based on the response by a VSCode team member.

References:
https://github.com/facebookincubator/create-react-app/issues/3602#issuecomment-352075571
https://github.com/Microsoft/vscode/issues/40293#issuecomment-352017028

Replaced `it's` with `its`

the code got updated from `detect()` to `choosePort` while the comment did not.