Upgrade to Bootstrap 5.1

[GuitarBro]

First PR here, so go easy on me. 😉

This one's fairly self-explanatory. I upgraded the Bootrstrap version from 3 to 5.1, attempting to preserve the general layout/content while making things look more modern.

Notable changes:

• Removed the dependency on FontAwesome 3.2.1 since Bootstrap 5 has their own icons.
• Removed the dependency on ekko lightbox as it was no longer being maintained beyond Bootstrap 4.x
  • In it's place is a simple lightbox replacement made with vanilla js. It should have all the existing functionality, though not the complete functionality of ekko lightbox. As a tradeoff, it is much more mobile-friendly
• Made compat more mobile-friendly, though on very small devices it may still require some horizontal scrolling.
• Updated the homepage banner to be full-width and behind the hero text. Personally I think the look is an improvement, but I understand this may be a matter of taste. 😛

Other things to mention: I'm not sure if there's any reason to have the jQuery dependency anymore since Bootstrap 5.x no longer requires it and ekko lightbox is gone. I left it just in case, but if those were the only places it was used, perhaps that should be removed as well to reduce page load times.

Pretty confident I got all the pages that needed attention, but I may have missed something so let me know if I need to revisit this.

Side note: CTRL/CtrlSTheWorld/GuitarBro all are me, just in case there's any confusion. Sorry about the inconsistency across git/github.

[leoetlino]

This is a little bit risky because old articles might be relying on Bootstrap CSS (for responsive embeds, and maybe layout and centering utils like text-center, float/pull-right, etc.) This will need to be carefully tested to ensure articles don't break.

[GuitarBro]

@leoetlino agreed. Is it possible to get a copy of the article data locally? I'd be happy to give it a look through for compatibility issues, I just lack the means to do it.

[GuitarBro]

Any chance I could get some visibility on this? It looks like #140 implements a dark theme that would be incompatible with Bootstrap 5.1 which is unfortunate. I was planning to work on implementing one of the compatible themes from bootstrap-dark-5 once this was approved, but without a way to verify the condition of the existing articles, this can't go in yet.

Perhaps since #140 has no conflicts, that one should be merged for the time being with a plan to eventually replace it with a bootstrap-dark-5 theme once this gets merged? Alternatively, I can work on adding it to this pull request if that makes more sense.