Remove wyrm_addons/pygments

[Blendify]

Fixes #503 By removing wyrm_addons/pygments we get full support of using native pygments to style code blocks

[Blendify]

This is not ready for review because I still need to fix things like text and spacing in our own sass

[Blendify]

This is ready for review now

[jessetan]

Looks pretty good as far as I can see, although the line-height feels a bit too much considering the font size and shape (I'm using macOS, which has Consolas). Previously the line-height was normal (== 1.2), now it is 1.5.
Screenshots below of possible other values. 1.5 looks better to me if the fontsize is a bit larger (14px?), but maybe I'm just nitpicking.

• line-height: 1.2 (current value in 0.2.4)
  
• line-height: 1.3
  
• line-height: 1.4
  
• line-height: 1.5 (new value)
  

[jessetan]

font-size and line-height can be moved to a new CSS rule for line numbering and actual code. That will prevent them from going out of sync in future.

pre.literal-block, div[class^='highlight'] pre, .linenodiv pre
    font-size: 12px
    line-height: normal

Adding pre.literal-block to this rule also aligns the font size for literal blocks, which look out of place now:

[Blendify]

Done

[jessetan]

Perhaps font-size: $base-font-size * 0.75 ?
(Also in other places in this PR)

[Blendify]

This would be a new behavior correct? Seems fine but maybe this is better for another PR?

[jessetan]

The behavior would be the same ($base-font-size is 16px), but indeed perhaps better to move to a new PR that adds a $code-font-size in _theme_variables.sass so we can be sure we have consistent font sizes.