Generate slug from post filenames

Rather than having Pandoc generate the id, which has the potential to change
over time and cause 404s, let's just generate the slug from the filename so
that the ids will never change.  This also solves the awkward question of
what the filename should be, since it was previously something arbitrary.

This mass rename was accomplished via this simple shell script:

  for p in *.meta; do
    slug=$( recsel -P slug "$p" | xargs basename )
    mv -v "${p/.meta/.md}" "${p:0:10}-$slug.md"
  done

with minor manual tweaks where I saw fit.  Of course, now I have some pretty
long filenames, which is undesirable.

The next step is to compare it with the slugs currently on mikegerwitz.com
and make them match.  That's the next commit, and should be pretty simple.

post/2012-10-06-trademarks-in-free-software.md

@@ -1,4 +1,7 @@
-# The use of trademarks in free software has always been a curious and unclear concept to me, primarily due to my ignorance on the topic
+# Trademarks in Free Software
+
+The use of trademarks in free software has always been a curious and unclear
+concept to me, primarily due to my ignorance on the topic.
 
 Trademarks, unless abused, are intended to protect consumers' interests---are
 they getting the brand that they think they're getting? If you download Firefox,

src/papers.rec

@@ -1,6 +1,6 @@
 id: git-horror-story
 type: post
-ref: 2012-05-22-git-horror-story
+ref: 2012-05-22-a-git-horror-story-repository-integrity-with-signed-commits
 
 id: coope
 type: latex
@@ -14,7 +14,7 @@ pubdate: 2013-05-13
 
 id: national-uproar
 type: post
-ref: 2013-06-10-national-uproar
+ref: 2013-06-10-national-uproar-a-comprehensive-overview-of-the-nsa-leaks-and-revelations
 
 id: gnu-kwindows
 type: post
@@ -22,20 +22,20 @@ ref: 2016-04-06-gnu-kwindows
 
 id: gitlab-gitorious-freesw
 type: post
-ref: 2015-05-20-gitlab-gitorious-freesw
+ref: 2015-05-20-gitlab-gitorious-and-free-software
 
 id: copyleft-vs-community
 type: post
-ref: 2013-08-13-copyleft-vs-community
+ref: 2013-08-13-freebsd-clang-and-gcc-copyleft-vs-community
 
 id: re-fsf-waste-away
 type: post
-ref: 2013-01-26-re-fsf-waste-high-priority
+ref: 2013-01-26-re-fsf-wastes-away-another-high-priority-project
 
 id: vlc-lgpl
 type: post
-ref: 2012-11-17-vlc-lgpl
+ref: 2012-11-17-vlcs-move-to-lgpl
 
 id: re-skype-let-spy
 type: post
-ref: 2013-01-30-re-skype-let-spy
+ref: 2013-01-30-re-who-does-skype-let-spy

src/post2meta

@@ -50,9 +50,11 @@ main && /^<h1 / {
 
     # Grab the generated id from the header and use it to
     # generate a complete slug.
-    printf "slug: %s/%s\n", \
-        gensub( /^([0-9]+)-([0-9]+).*$/, "\\1/\\2", "", name[0] ), \
-        gensub( /^<h[^>]+ id="([^"]+)".*$/, "\\1", "" )
+    printf "slug: %s\n", \
+        gensub( /^([0-9]+)-([0-9]+)-[0-9]+-(.*)\.[a-z]+$/,
+                "\\1/\\2/\\3",
+                "",
+                name[0] )
 
     # Skip the date line immediately following the header and grab the first
     # line of the abstract.