Eval: switch(), bugfix getting possible values
Re-think getting global_data; get property values for types where necessary
Test: icon_types
Merge branch 'master' into icon_png
Stat: move cache to class; fun to clear cache
Global Data: init with None; clear stat cache after update
Eval: debug(), bugfix
Eval: switch(), re-write possible_values
Types 'image', 'image_png': get dimensions of images, save to global_data
repeat-image: support repeat-image-align