add deadlinks plugin

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "plugins/pelican-encrypt-content"]
 	path = plugins/pelican-encrypt-content
 	url = https://github.com/mindcruzer/pelican-encrypt-content.git
+[submodule "plugins/pelican-deadlinks"]
+	path = plugins/pelican-deadlinks
+	url = https://github.com/silentlamb/pelican-deadlinks.git

pelican/pelicanconf.py

@@ -35,7 +35,9 @@ DEFAULT_PAGINATION = 20
 USE_FOLDER_AS_CATEGORY = True  # Use directories in content to specify the category
 DEFAULT_CATEGORY = 'none'
 
-PLUGINS = ['encrypt_content']
+PLUGINS_PATH = ['plugins']
+
+PLUGINS = ['encrypt_content', 'deadlinks']
 
 ENCRYPT_CONTENT = {
     'title_prefix': '[Encrypted]',

plugins/pelican-deadlinks

@@ -0,0 +1 @@
+Subproject commit 8b49b594591ded55ba20b74c54c12a566fe8e9cc

requirements.txt

@@ -1,6 +1,11 @@
+beautifulsoup4==4.7.1
 blinker==1.4
+bs4==0.0.1
+certifi==2019.3.9
+chardet==3.0.4
 docutils==0.14
 feedgenerator==1.9
+idna==2.8
 Jinja2==2.10.1
 Markdown==3.1.1
 MarkupSafe==1.1.1
@@ -9,5 +14,8 @@ pycrypto==2.6.1
 Pygments==2.4.1
 python-dateutil==2.8.0
 pytz==2019.1
+requests==2.22.0
 six==1.12.0
+soupsieve==1.9.1
 Unidecode==1.0.23
+urllib3==1.25.3