Refactor & implement lineWidth

[cyntler]

Closes #28

• add .nvmrc files with Node v16
• move hamburger components to src/components
• add new prop lineWidth
• install & config Prettier for the project

[luukdv]

Thanks so much for the effort! I didn't know you had this planned… I've actually been working on version 3.0 that's quite an overhaul, which should solve other use cases as well (for example being able to control both barWidth and barHeight as described in https://github.com/luukdv/hamburger-react/issues/28).

[cyntler]

@luukdv Oh, okay! :) I understand. So in this situation I think we can close the pull request. I will wait for you changes! :)

[NeeshSamsi]

@luukdv Is there any progress on the 3.0? Would love to have the lineWidth prop added at some point. This is by far the best library I've found for effortless hamburger menus.

[luukdv]

Thank you! Update about v3.0: Looking for new owner