Javascript Coding Style

#CS400 → #CS499 Javascript

#CS400 Use the w3school JS convention

Use the w3school JS convention where not specified otherwise by our coding style.

#CS401 Use 2 spaces indentation

To be consistent with our C/C++ coding style, we must use 2 spaces (instead of 4) to indent code.

#CS402 Don't use unneeded curly brackets

To be consistent with our C/C++ coding style, don't use curly brackets when not needed (e.g., for single instruction blocks).

#CS403 Use ESLint linter (atom package: linter-eslint)

All the errors reported by ESLint based on the https://github.com/omichel/webots/blob/master/.eslintrc.json configuration file should be fixed. Warnings may be accepted.