Build the pagetools sprite programatically with imagemagick

This makes it easier to modify or extend the icons in the sprite.
Just place the source files in the pagetools directory and run the build
script.

lib/tpl/dokuwiki/images/pagetools-build.sh

+#!/bin/sh
+#
+# This script generates a sprite from the unprocessed toolbar icons by combining them
+# and overlaying a color layer for the active state
+#
+# The final sprite is optimized with optipng
+#
+# The script currently expects a Linux system with current versions of the imagemagick
+# and optipng binaries in the path
+#
+# @author Andreas Gohr <andi@splitbrain.org>
+
+OUT=`dirname $0`
+IN="$OUT/pagetools"
+
+if [ ! -d "$IN" ]; then
+    echo "Input folder $IN not found"
+    exit 1
+fi
+
+if [ -z "$TEMP" ]; then
+    TEMP="/tmp"
+fi
+
+if [ ! -d "$TEMP" ]; then
+    echo "No temp directory available"
+    exit 1
+fi
+
+# add up all images twice
+montage `for X in $IN/*.png; do echo -n "$X $X "; done`  -background transparent -tile 1x -geometry 30x45 -gravity north $TEMP/icons.png
+
+# darken the image
+convert $TEMP/icons.png \( +clone -fill '#cccccc' -colorize 100% \) -compose multiply -composite $TEMP/darkicons.png
+
+# create the mask to highlight an active icon
+convert -size 30x30 xc:'#2b73b7' -gamma 0.7 $TEMP/active.png
+
+# create the full mask
+montage `for X in $IN/*.png; do echo -n "$TEMP/active.png "; done` -background transparent -tile 1x -geometry 30x60+0+15 -gravity south $TEMP/activemask.png
+
+# apply mask
+convert $TEMP/darkicons.png $TEMP/activemask.png  \
+\( -clone 0 -alpha extract \) \
+\( -clone 0 -clone 1 -compose overlay -composite \) \
+-delete 0,1 +swap -alpha off -compose copy_opacity -composite $OUT/pagetools-sprite.png
+
+# optimize final sprite
+optipng -o5 $OUT/pagetools-sprite.png
+
+# remove temporary images
+rm -f $TEMP/icons.png
+rm -f $TEMP/darkicons.png
+rm -f $TEMP/active.png
+rm -f $TEMP/activemask.png
+