Remove blog cover from posts

This makes for a neat and minimal post view, while also removing the
need for default.hbs.

Also changed around the layout nesting a bit and cleaned out the
styling.
Fix index .header padding
Tweak post images and code

Center images and prevent upscaling; add a bit of left and right
padding to inline code.
Move Pagination inside Partials
Use only single color for text

Black had a bit too much contrast against a pure white background.
Fix pagination

Add in conditionals for navigation arrows
Add classes to everythng
Fix responsiveness
Add night mode to blog posts

Uses jQuery which is bad, trying to find out a way to do it without
that.
Night mode with pure javascript instead of jQuery
Simplify post footer on index
Add if statement to showing author image in post footer
Merge pull request #1 from iiroj/Minimal-post-view

Minimal post view