Add "make icons_geom" convenience target

Generates icons from the blend file in lib.

release/datafiles/blender_icons_geom_update.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+
+# This script updates icons from the SVG file
+import os
+import subprocess
+import sys
+
+def run(cmd):
+    print("   ", " ".join(cmd))
+    subprocess.check_call(cmd)
+
+BASEDIR = os.path.abspath(os.path.dirname(__file__))
+ROOTDIR = os.path.normpath(os.path.join(BASEDIR, "..", ".."))
+
+blender_bin = os.environ.get("BLENDER_BIN", "blender")
+if not os.path.exists(blender_bin):
+    blender_bin = os.path.join(ROOTDIR, "blender.bin")
+
+icons_blend = (
+    os.path.join(ROOTDIR, "..", "lib", "resources", "icon_geom.blend"),
+)
+
+# create .dat pixmaps (which are stored in git)
+for blend in icons_blend:
+    cmd = (
+        blender_bin, "--background", "--factory-startup", "-noaudio",
+        blend,
+        "--python", os.path.join(BASEDIR, "blender_icons_geom.py"),
+        "--",
+        "--output-dir", os.path.join(BASEDIR, "icons"),
+    )
+    run(cmd)