Bump Jekyll and co

Gemfile

@@ -1,11 +1,12 @@
 source "https://rubygems.org"
 
-gem "jekyll", "~> 3.1"
-gem 'jekyll-gist'
-gem 'kramdown'
+gem "jekyll", "~> 3.4.0"
 # with Ruby 2.0 on OS X, you may need to install
 # it manually with --with-iconv-dir:
 #
 # gem install iconv -- --with-iconv-dir=~/.rvm/usr
 gem "iconv"
 gem "albino"
+gem "redcarpet"
+gem "pygments.rb"
+gem "rake", "~> 12.0"

_config.yml

@@ -1,8 +1,9 @@
 source:      .
 destination: ./_site
-layouts_dir: ./_layouts
 plugins_dir: ./_plugins
 exclude: [bin, CNAME, Gemfile, Gemfile.lock, README.md]
-markdown: kramdown
 permalink: /:title
-highlighter: rouge
+highlighter: pygments
+markdown: redcarpet
+redcarpet:
+  extensions: ["no_intra_emphasis", "fenced_code_blocks", "autolink", "tables", "with_toc_data"]