Add a feature to report all references to a URL [cherry-pick]

[cjmayo]

This is 2a9ec3f from #663 cherry-picked with the following resolved:

--- a/linkcheck/checker/urlbase.py
+++ b/linkcheck/checker/urlbase.py
@@@ -397,9 -384,14 +399,18 @@@ class UrlBase
              self.info.append(s)
  
      def set_cache_url(self):
-         """Set the URL to be used for caching."""
+         """Set the URLs to be used for caching."""
+ 
          if "AnchorCheck" in self.aggregate.config["enabledplugins"]:
++<<<<<<< HEAD
 +            self.cache_url = self.url
++=======
+             log.debug(
+                 LOG_CHECK,
+                 "set_cache_url: self.url: %s; self.anchor: %s; self.urlparts[4]: %s",
+                 self.url, self.anchor, self.urlparts[4])
+             self.result_cache_url = self.url
++>>>>>>> 2a9ec3fe (Add a feature to report all references to a URL)
          else:
              # remove anchor from cached target url since we assume
              # URLs with different anchors to have the same content
diff --cc linkcheck/data/linkcheckerrc
index cd1d0765,95013c74..00000000
--- a/linkcheck/data/linkcheckerrc
+++ b/linkcheck/data/linkcheckerrc
@@@ -9,21 -9,17 +9,27 @@@
  # print status output
  #status=1
  # change the logging type
 -#log=xml
 +#log=text
  # turn on/off --verbose
 -#verbose=1
 +#verbose=0
  # turn on/off --warnings
++<<<<<<< HEAD
 +#warnings=1
++=======
+ #warnings=0
+ # turn on/off --allrefs
+ #reportallreferences=1
++>>>>>>> 2a9ec3fe (Add a feature to report all references to a URL)
  # turn on/off --quiet
 -#quiet=1
 -# additional file output
 +#quiet=0
 +# additional file output, example:
  #fileoutput = text, html, gml, sql
 +# errors to ignore (URL regular expression, message regular expression)
 +#ignoreerrors=
 +# ignore all errors for broken.example.com:
 +#  ^https?://broken.example.com/
 +# ignore SSL errors for dev.example.com:
 +#  ^https://dev.example.com/ ^SSLError .*
  
  
  ##################### logger configuration ##########################