Simplify use of URLs in text files.

In several cases our text files had commentary like this:
# Egypt to cancel daylight saving time
# <a href="http://www.almasryalyoum.com/en/node/407168">
# http://www.almasryalyoum.com/en/node/407168
# </a>
where lines 2 and 4 let the file be viewed by a browser with the
URL being clickable.  In practice this approach does not work with
many modern browsers (I tested with Firefox and with Chrome) and
it clutters up the data, so in cases like the above this patch
removes lines 2 and 4.
(Problem reported by Steffen "Daode" Nurpmeso.)

antarctica

@@ -1,16 +1,13 @@
-# <pre>
 # This file is in the public domain, so clarified as of
 # 2009-05-17 by Arthur David Olson.
 
 # From Paul Eggert (1999-11-15):
 # To keep things manageable, we list only locations occupied year-round; see
-# <a href="http://www.comnap.aq/comnap/comnap.nsf/P/Stations/">
 # COMNAP - Stations and Bases
-# </a>
+# <http://www.comnap.aq/comnap/comnap.nsf/P/Stations/>
 # and
-# <a href="http://www.spri.cam.ac.uk/bob/periant.htm">
 # Summary of the Peri-Antarctic Islands (1998-07-23)
-# </a>
+# <http://www.spri.cam.ac.uk/bob/periant.htm>
 # for information.
 # Unless otherwise specified, we have no time zone information.
 #
@@ -65,9 +62,9 @@ Rule	ChileAQ	2012	max	-	Sep	Sun>=2	4:00u	1:00	S
 # Australia - territories
 # Heard Island, McDonald Islands (uninhabited)
 #	previously sealers and scientific personnel wintered
-#	<a href="http://web.archive.org/web/20021204222245/http://www.dstc.qut.edu.au/DST/marg/daylight.html">
 #	Margaret Turner reports
-#	</a> (1999-09-30) that they're UTC+5, with no DST;
+#	<http://web.archive.org/web/20021204222245/http://www.dstc.qut.edu.au/DST/marg/daylight.html>
+#	(1999-09-30) that they're UTC+5, with no DST;
 #	presumably this is when they have visitors.
 #
 # year-round bases
@@ -84,14 +81,10 @@ Rule	ChileAQ	2012	max	-	Sep	Sun>=2	4:00u	1:00	S
 # The changes occurred on 2009-10-18 at 02:00 (local times).
 #
 # Government source: (Australian Antarctic Division)
-# <a href="http://www.aad.gov.au/default.asp?casid=37079">
 # http://www.aad.gov.au/default.asp?casid=37079
-# </a>
 #
 # We have more background information here:
-# <a href="http://www.timeanddate.com/news/time/antarctica-new-times.html">
 # http://www.timeanddate.com/news/time/antarctica-new-times.html
-# </a>
 
 # From Steffen Thorsen (2010-03-10):
 # We got these changes from the Australian Antarctic Division: ...
@@ -106,9 +99,7 @@ Rule	ChileAQ	2012	max	-	Sep	Sun>=2	4:00u	1:00	S
 # - Mawson station stays on UTC+5.
 #
 # Background:
-# <a href="http://www.timeanddate.com/news/time/antartica-time-changes-2010.html">
 # http://www.timeanddate.com/news/time/antartica-time-changes-2010.html
-# </a>
 
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Casey	0	-	zzz	1969
@@ -132,15 +123,12 @@ Zone Antarctica/Mawson	0	-	zzz	1954 Feb 13
 						# Mawson Time
 			5:00	-	MAWT
 # References:
-# <a href="http://www.antdiv.gov.au/aad/exop/sfo/casey/casey_aws.html">
 # Casey Weather (1998-02-26)
-# </a>
-# <a href="http://www.antdiv.gov.au/aad/exop/sfo/davis/video.html">
+# <http://www.antdiv.gov.au/aad/exop/sfo/casey/casey_aws.html>
 # Davis Station, Antarctica (1998-02-26)
-# </a>
-# <a href="http://www.antdiv.gov.au/aad/exop/sfo/mawson/video.html">
+# <http://www.antdiv.gov.au/aad/exop/sfo/davis/video.html>
 # Mawson Station, Antarctica (1998-02-25)
-# </a>
+# <http://www.antdiv.gov.au/aad/exop/sfo/mawson/video.html>
 
 # Brazil - year-round base
 # Comandante Ferraz, King George Island, -6205+05824, since 1983/4
@@ -192,9 +180,8 @@ Zone Antarctica/DumontDUrville 0 -	zzz	1947
 			0	-	zzz	1956 Nov
 			10:00	-	DDUT	# Dumont-d'Urville Time
 # Reference:
-# <a href="http://en.wikipedia.org/wiki/Dumont_d'Urville_Station">
 # Dumont d'Urville Station (2005-12-05)
-# </a>
+# <http://en.wikipedia.org/wiki/Dumont_d'Urville_Station>
 
 # Germany - year-round base
 # Georg von Neumayer, -7039-00815
@@ -216,9 +203,8 @@ Zone Antarctica/DumontDUrville 0 -	zzz	1947
 Zone Antarctica/Syowa	0	-	zzz	1957 Jan 29
 			3:00	-	SYOT	# Syowa Time
 # See:
-# <a href="http://www.nipr.ac.jp/english/ara01.html">
 # NIPR Antarctic Research Activities (1999-08-17)
-# </a>
+# <http://www.nipr.ac.jp/english/ara01.html>
 
 # S Korea - year-round base
 # King Sejong, King George Island, -6213-05847, since 1988
@@ -278,8 +264,8 @@ Zone Antarctica/Troll	0	-	zzz	2005 Feb 12
 #	year-round from 1960/61 to 1992
 
 # Vostok, since 1957-12-16, temporarily closed 1994-02/1994-11
-# <a href="http://quest.arc.nasa.gov/antarctica/QA/computers/Directions,Time,ZIP">
-# From Craig Mundell (1994-12-15)</a>:
+# From Craig Mundell (1994-12-15)
+# <http://quest.arc.nasa.gov/antarctica/QA/computers/Directions,Time,ZIP>:
 # Vostok, which is one of the Russian stations, is set on the same
 # time as Moscow, Russia.
 #