São Tomé and Príncipe has switched to +01

(Thanks to Steffen Thorsen.)
* NEWS: Mention this.
* backzone: Move Africa/Sao_Tome from here ...
* africa: ... to here, add 2018 transition to +01, and
correct the pre-1912 offset for Lisbon Mean Time.
* zone1970.tab (ST): Break out into different entry.

Author: eggert

NEWS

@@ -2,6 +2,11 @@ News for the tz database
 
 Unreleased, experimental changes
 
+  Changes to past and future time stamps
+
+    São Tomé and Príncipe switched from +00 to +01 on 2018-01-01 at
+    00:00.  (Thanks to Steffen Thorsen.)
+
   Changes to future time stamps
 
     Starting in 2018 southern Brazil will begin DST on November's

africa

@@ -158,7 +158,6 @@ Link Africa/Abidjan Africa/Freetown	# Sierra Leone
 Link Africa/Abidjan Africa/Lome		# Togo
 Link Africa/Abidjan Africa/Nouakchott	# Mauritania
 Link Africa/Abidjan Africa/Ouagadougou	# Burkina Faso
-Link Africa/Abidjan Africa/Sao_Tome	# São Tomé and Príncipe
 Link Africa/Abidjan Atlantic/St_Helena	# St Helena
 
 # Djibouti
@@ -1037,6 +1036,11 @@ Zone	Indian/Reunion	3:41:52 -	LMT	1911 Jun # Saint-Denis
 #	Inaccessible, Nightingale: uninhabited
 
 # São Tomé and Príncipe
+Zone	Africa/Sao_Tome	 0:26:56 -	LMT	1884
+			-0:36:45 -	LMT	1912 # Lisbon Mean Time
+			 0:00	-	GMT	2018 Jan 1 00:00
+			 1:00	-	WAT
+
 # Senegal
 # See Africa/Abidjan.
 

backzone

@@ -237,11 +237,6 @@ Zone Africa/Porto-Novo	0:10:28	-	LMT	1912 Jan  1
 			0:00	-	GMT	1934 Feb 26
 			1:00	-	WAT
 
-# São Tomé and Príncipe
-Zone	Africa/Sao_Tome	 0:26:56 -	LMT	1884
-			-0:36:32 -	LMT	1912 # Lisbon Mean Time
-			 0:00	-	GMT
-
 # Mali (northern)
 Zone	Africa/Timbuktu	-0:12:04 -	LMT	1912
 			 0:00	-	GMT

zone1970.tab

@@ -132,7 +132,7 @@ CA	+6043-13503	America/Whitehorse	Pacific - Yukon (south)
 CA	+6404-13925	America/Dawson	Pacific - Yukon (north)
 CC	-1210+09655	Indian/Cocos
 CH,DE,LI	+4723+00832	Europe/Zurich	Swiss time
-CI,BF,GM,GN,ML,MR,SH,SL,SN,ST,TG	+0519-00402	Africa/Abidjan
+CI,BF,GM,GN,ML,MR,SH,SL,SN,TG	+0519-00402	Africa/Abidjan
 CK	-2114-15946	Pacific/Rarotonga
 CL	-3327-07040	America/Santiago	Chile (most areas)
 CL	-5309-07055	America/Punta_Arenas	Region of Magallanes
@@ -321,6 +321,7 @@ SE	+5920+01803	Europe/Stockholm
 SG	+0117+10351	Asia/Singapore
 SR	+0550-05510	America/Paramaribo
 SS	+0451+03137	Africa/Juba
+ST	+0020+00644	Africa/Sao_Tome
 SV	+1342-08912	America/El_Salvador
 SY	+3330+03618	Asia/Damascus
 TC	+2128-07108	America/Grand_Turk