Some code cleanup

[vincentfretin]

• Remove dead code, unused imports, unused variables.
• Use import/export everywhere, latest wepback/babel don't allow to use module.exports if you used one import statement.
• Specify a prettier config with option singleQuote to match the current code. I didn't reformatted the files with prettier in this PR.
• Disable the eslint space-before-function-paren rule that conflicts with how prettier format the files.
• Fix eslint errors.

[vincentfretin]

eslint errors down to 15 errors instead of 350 errors

[vincentfretin]

I'll fix the remaining eslint errors later then this PR should be good to merge if there is no objection.

[vincentfretin]

I fixed all remaining eslint issues, excepted those:
npm run lint

src/components/components/Mixins.js
  20:5  error  Do not use setState in componentDidUpdate  react/no-did-update-set-state

I'll fix this one as part of the react update in #641.

src/index.js
  104:11  error  'geometry' is defined but never used  no-unused-vars
  105:11  error  'material' is defined but never used  no-unused-vars

This is already fixed in #638

This PR is ready to be merged after #638.

[vincentfretin]

npm run prettier will reformat those files

	modifié :         src/components/Main.js
	modifié :         src/components/components/CommonComponents.js
	modifié :         src/components/components/Component.js
	modifié :         src/components/scenegraph/Toolbar.js
	modifié :         src/components/viewport/CameraToolbar.js
	modifié :         src/lib/EditorControls.js
	modifié :         src/lib/cameras.js
	modifié :         src/lib/raycaster.js
	modifié :         src/lib/viewport.js

but we can do that in a separate PR, I created the issue #642 for this.

[dmarcos]

Does this enforce 80 character lines? If that's the case not sure if these days makes much sense. In today's displays aspect ratio vertical space is more of a premium than horizontal

[vincentfretin]

It's actually the default.

[vincentfretin]

All files are already using the 80 characters limit actually, so no real change here.

[dmarcos]

This one is ready to go? Thanks for the patience.

[vincentfretin]

Yes, please merge.