Add mapserver config for testing.

Added a minimal mapserver config "coastline.map" and a script "render_image.sh"
that uses mapservers shp2img program to render the polygons.

coastline.map

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+#
+#  Mapserver configuration
+#
+#  For rendering using this file see render_image.sh.
+#
+MAP
+    NAME coastline
+    IMAGECOLOR 255 255 255
+
+    LAYER
+        NAME polygons
+        TYPE POLYGON
+        STATUS ON
+        CONNECTIONTYPE OGR
+        CONNECTION "coastline-mapserver.db"
+        DATA "polygons"
+        CLASS
+            STYLE
+                COLOR 0 0 0
+            END
+        END
+    END
+
+END

render_image.sh

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+#!/bin/sh
+#
+#  render_image.sh [DBFILE]
+#
+#  Render polygons in DBFILE using shp2img program from mapserver.
+#  Automatically detects SRID and renders accordingly.
+#  If no DBFILE is given, testdata.db is used.
+#
+
+WIDTH=2048
+
+if [ "x$1" = "x" ]; then
+    DBFILE=testdata.db
+else
+    DBFILE=$1
+fi
+
+SRID=`sqlite3 $DBFILE "SELECT srid FROM geometry_columns WHERE f_table_name='polygons'"`
+
+if [ "$SRID" = "4326" ]; then
+    # If SRID is WGS84 the image height is half its width
+    HEIGHT=`expr $WIDTH / 2`
+    EXTENT="-180 -90 180 90"
+else
+    # If SRID is 3857 (Mercator) the image height is the same as its width
+    HEIGHT=$WIDTH
+    EXTENT="-20037508.342789244 -20037508.342789244 20037508.342789244 20037508.342789244"
+fi
+
+rm -f coastline-mapserver.db
+ln -s $DBFILE coastline-mapserver.db
+shp2img -m coastline.map -l polygons -i PNG -o polygons.png -s $WIDTH $HEIGHT -e $EXTENT
+rm -f coastline-mapserver.db
+