Refactor: rename js&css directory

[4yman-0]

This PR removes the need for js&css since every directory (extension, menu etc.) has js and css subfolders. www.youtube.com was also renamed to yt.be.

edit: d942d8f and ae968c7

[ImprovedTube]

hi! and thanks @4yman-el js & css are friends, stuff is short

[4yman-0]

stuff is short

OK, i'll rename it again

[4yman-0]

How about res?

[raszpl]

One one hand modern file systems can handle & no problem, on the other hand separating CSS to its own directory does feel much cleaner and nicer.

[ImprovedTube]

TYSM again! 4yman-el i'm story to be 'stubborn' this time to delay this in favor of our habit clicking through exactly this structure for right now and once we change it then we might change more. (Draft is not what i meant but #later or #optional-inspiration)

(and the price renaming costs, is adding an extra page to to edit histories on github to each of the files)

before doing much more of this i would like to prepare command lines still to rewrite the commit history most conveniently. (or hope to find the perfect ready made tool for that)

on the other hand separating CSS to its own directory does feel much cleaner and nicer.

yet hardly separated on the client-side. @raszpl / Some of the css&js pairs /neighbors might be edited at once. i'd consider to mix in html, json, sql(-lite), csv at need & call the folder (browser-)code.

And, not said yet: Since this project sometimes is about entertainment (youtube) and young users, it would makes sense that the naming fit a bit of a broader audience (rare/new/hobby developers) who might also potentially fix something little sometimes.

[ImprovedTube]

Makes sense for today?
Wish i could already /first make productive contributors reply to bigger concepts /visions like:

• https://github.com/code-charity/Bulk-Contributor
  • https://github.com/code-charity/crowd-fixes
    • and in future a lot of our css & js could be converted from & to the rule format/s of ublockOrigin & Adblock. To eventually be versatile and Bulk managed. To automatically contribute to a few projects all at once and have this project inherit work form others too.

[ImprovedTube]

@4yman-el you chose

[ImprovedTube]

inviting you to the organisation so that you can set labels in future (or assign. or close duplicates)

[4yman-0]

thanks for 8cab0ca!

[4yman-0]

@ImprovedTube Please review now.

[4yman-0]

Each PR has its own purpose, please merge or push to master instead of this fork/branch. I was confused by the commits named typo, - etc.
edit: small typo