render: add test for c1a3 fan material

https://github.com/w23/xash3d-fwgs/issues/669

render/rendertest.py

@@ -10,6 +10,7 @@ import subprocess
 ROOT = os.path.dirname(os.path.abspath(__file__))
 
 # TODO load all saves from the save/ dir
+# TODO rename to <map>_<description>_<issue(opt)>
 saves = [
 	'brush2_01',
 	'brush_01',
@@ -17,6 +18,7 @@ saves = [
 	'c0a0d_emissive',
 	'light_01',
 	'additive_cullback',
+	'c1a3_fan_material_669',
 ]
 
 displays = {