Reduce snowy tiles to XPM palette.

ChangeLog.rtro

@@ -1,6 +1,21 @@
 ------------------------
 Changes for top of trunk
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+2023-08-02 Daniel Hawkins
+	* ground/Winter/drifts.rtro.111.png,
+	  ground/Winter/drifts2.rtro.111.png,
+	  ground/Winter/evil_ice.rtro.11*.png,
+	  ground/Winter/glacier.rtro.111.png,
+	  ground/Winter/ice.rtro.111.png,
+	  ground/Winter/ice2.rtro.111.png,
+	  ground/Winter/istone.rtro.111.png,
+	  ground/Winter/snow.rtro.111.png,
+	  ground/Winter/snow2.rtro.111.png,
+	  ground/Winter/snow4.rtro.111.png,
+	  ground/Winter/snow5.rtro.111.png,
+	  ground/Winter/snowroad.rtro.111.png,
+	  ground/Winter/snowroad2.rtro.111.png: Reduce to XPM palette.
+
 2023-08-01 Daniel Hawkins
 	* misc/shipswheel.rtro.111.png: Rederive from base image in a manner to avoid partial transparency
 	    and adhere to the XPM palette.