Fixed theme + migrated to newer Hugo features

[kdevo]

Hi there,

first: Thanks for the cool theme!

I just applied the needed changes for #69 and got this theme working again.

Additionally, I did the following improvements ✨:

• Implement native cache busting via the newer Hugo Pipes:
  • Use fingerprinting for the resource filenames
  • No additional setup needed anymore
  • Move to the newer assets directory:
    • Use the SCSS (sass) sources and convert them to CSS using resources.ToCSS
    • Use resources.Minify
    • Remove minified files where possible and only keep the sources
• Remove Hugo linter warnings:
  • Use .Site.RegularPages instead of .Data.Pages where needed
  • Use .File.UniqueID instead of .UniqueID
  • Use {{ with .OutputFormats.Get "RSS" }} ...
  • Remove deprecated Hugo generator meta tag (will be injected automatically, anyways)
• Pin version to Hugo 0.5 (maybe 0.43 would do the job, too)

⚠️ Please test this PR thoroughly before merging into master.

I just rapidly wanted to share my changes and help out a bit, but didn't have the time to test everything.

[tomanistor]

I appreciate the PR @kdevo! Let me test it out and I'll merge it in if it works.

[kdevo]

Just a note: As already commented in the yet closed #69 I forked this theme but still wanted to fix the above bug in the original merge request regarding the contact form functionality.
This was the only bug I encountered.

[tomanistor]

Thanks for the updates @kdevo! I've just tested on my own site and merged into master.