Revert "upgrade to Jekyll 4"

This reverts commit 2437fdc5f71b87a4595b27fdbd74663512fe7d32.

OMFG: https://github.com/jekyll/github-metadata/issues/242

6 files changed, 63 insertions, 39 deletions

diff --git a/.gitignore b/.gitignore
index 218813a..921f829 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,2 @@
-/.jekyll-cache/
 /_site/
 /.wget/
diff --git a/Gemfile b/Gemfile
index 81d0077..7fcfd0d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,9 @@
 source 'https://rubygems.org'
-gem 'jekyll', '~> 4'
+gem 'jekyll', '~> 3'
 
 gem 'jekyll-github-metadata'
 gem 'jekyll-paginate'
 gem 'jekyll-tidy'
+# Why is this not a dependency of Jekyll? Considering that without
+# kramdown-parser-gfm, Jekyll will error out.
+gem 'kramdown-parser-gfm'
diff --git a/Gemfile.lock b/Gemfile.lock
index 3d57c5c..44afe3d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,46 +1,63 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.8.1)
-      public_suffix (>= 2.0.2, < 6.0)
+    addressable (2.8.0)
+      public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
     concurrent-ruby (1.1.10)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
     eventmachine (1.2.7)
-    faraday (2.6.0)
-      faraday-net_http (>= 2.0, < 3.1)
+    faraday (1.10.0)
+      faraday-em_http (~> 1.0)
+      faraday-em_synchrony (~> 1.0)
+      faraday-excon (~> 1.1)
+      faraday-httpclient (~> 1.0)
+      faraday-multipart (~> 1.0)
+      faraday-net_http (~> 1.0)
+      faraday-net_http_persistent (~> 1.0)
+      faraday-patron (~> 1.0)
+      faraday-rack (~> 1.0)
+      faraday-retry (~> 1.0)
       ruby2_keywords (>= 0.0.4)
-    faraday-net_http (3.0.1)
+    faraday-em_http (1.0.0)
+    faraday-em_synchrony (1.0.0)
+    faraday-excon (1.1.0)
+    faraday-httpclient (1.0.1)
+    faraday-multipart (1.0.3)
+      multipart-post (>= 1.2, < 3)
+    faraday-net_http (1.0.1)
+    faraday-net_http_persistent (1.2.0)
+    faraday-patron (1.0.0)
+    faraday-rack (1.0.0)
+    faraday-retry (1.0.3)
     ffi (1.15.5)
     forwardable-extended (2.6.0)
     htmlbeautifier (1.4.2)
     htmlcompressor (0.4.0)
     http_parser.rb (0.8.0)
-    i18n (1.12.0)
+    i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (4.2.2)
+    jekyll (3.9.2)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
-      i18n (~> 1.0)
-      jekyll-sass-converter (~> 2.0)
+      i18n (~> 0.7)
+      jekyll-sass-converter (~> 1.0)
       jekyll-watch (~> 2.0)
-      kramdown (~> 2.3)
-      kramdown-parser-gfm (~> 1.0)
+      kramdown (>= 1.17, < 3)
       liquid (~> 4.0)
-      mercenary (~> 0.4.0)
+      mercenary (~> 0.3.3)
       pathutil (~> 0.9)
-      rouge (~> 3.0)
+      rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-      terminal-table (~> 2.0)
-    jekyll-github-metadata (2.15.0)
+    jekyll-github-metadata (2.14.0)
       jekyll (>= 3.4, < 5.0)
       octokit (~> 4.0, != 4.4.0)
     jekyll-paginate (1.1.0)
-    jekyll-sass-converter (2.2.0)
-      sassc (> 2.0.1, < 3.0)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
     jekyll-tidy (0.2.2)
       htmlbeautifier
       htmlcompressor
@@ -55,37 +72,39 @@ GEM
     listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    mercenary (0.4.0)
-    octokit (4.25.1)
-      faraday (>= 1, < 3)
-      sawyer (~> 0.9)
+    mercenary (0.3.6)
+    multipart-post (2.1.1)
+    octokit (4.22.0)
+      faraday (>= 0.9)
+      sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (5.0.0)
-    rb-fsevent (0.11.2)
+    public_suffix (4.0.7)
+    rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.5)
-    rouge (3.30.0)
+    rouge (3.28.0)
     ruby2_keywords (0.0.5)
     safe_yaml (1.0.5)
-    sassc (2.4.0)
-      ffi (~> 1.9)
-    sawyer (0.9.2)
+    sass (3.7.4)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    sawyer (0.8.2)
       addressable (>= 2.3.5)
-      faraday (>= 0.17.3, < 3)
-    terminal-table (2.0.0)
-      unicode-display_width (~> 1.1, >= 1.1.1)
-    unicode-display_width (1.8.0)
+      faraday (> 0.8, < 2.0)
 
 PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
-  jekyll (~> 4)
+  jekyll (~> 3)
   jekyll-github-metadata
   jekyll-paginate
   jekyll-tidy
+  kramdown-parser-gfm
 
 BUNDLED WITH
    2.3.13
diff --git a/_config.yml b/_config.yml
index 5a45eb7..21d7d34 100644
--- a/_config.yml
+++ b/_config.yml
@@ -6,8 +6,11 @@ show_drafts: true
 strict_front_matter: true
 
 exclude:
+  - Gemfile
+  - Gemfile.lock
   - Makefile
   - README.md
+  - vendor/
 
 defaults:
   - scope:
diff --git a/_posts/2021-04-10-collapsible.md b/_posts/2021-04-10-collapsible.md
index bdd4585..214c408 100644
--- a/_posts/2021-04-10-collapsible.md
+++ b/_posts/2021-04-10-collapsible.md
@@ -17,7 +17,7 @@ snippets:
 Snippets are defined in exactly the same way as in the [other post].
 Just set a front matter value to make them collapsible, and voilà!
 
-[other post]: {% post_url 2021-04-09-snippets %}
+[other post]: {{ site.baseurl }}{% post_url 2021-04-09-snippets %}
 
 {% include jekyll-theme/snippets/section.html section_id='hello' %}
 
diff --git a/index.md b/index.md
index 6cdd755..24f9146 100644
--- a/index.md
+++ b/index.md
@@ -20,18 +20,18 @@ navbar:
     <h4 class="list-group-item-heading">categories</h4>
     <p class="list-group-item-text">List of post categories (includes links to each category's page)</p>
   </a>
-  <a href="{% post_url 2021-04-09-snippets %}" class="list-group-item">
+  <a href="{{ site.baseurl }}{% post_url 2021-04-09-snippets %}" class="list-group-item">
     <h4 class="list-group-item-heading">code snippets</h4>
     <p class="list-group-item-text">Easily include code snippets in your posts</p>
   </a>
-  <a href="{% post_url 2021-04-10-collapsible %}" class="list-group-item">
+  <a href="{{ site.baseurl }}{% post_url 2021-04-10-collapsible %}" class="list-group-item">
     <h4 class="list-group-item-heading">collapsible snippets</h4>
   </a>
-  <a href="{% post_url 2022-03-21-shell %}" class="list-group-item">
+  <a href="{{ site.baseurl }}{% post_url 2022-03-21-shell %}" class="list-group-item">
     <h4 class="list-group-item-heading">shell commands</h4>
     <p class="list-group-item-text">Clearly separate shell commands and their outputs from one another</p>
   </a>
-  <a href="{% post_url 2021-04-08-mathjax %}" class="list-group-item">
+  <a href="{{ site.baseurl }}{% post_url 2021-04-08-mathjax %}" class="list-group-item">
     <h4 class="list-group-item-heading">typesetting math</h4>
   </a>
 </div>