(UTF8 string) In "Image Plane(RMB)" dialog,Crash when treat to UTF8 name.

[tkbd]

Note:This problem only occured when using "Image Plane" dialog option.
"Image Plane(LMB)" command is no problem.

How to recreate this problem?

1. To load file by "Image Plane" command(RMB).(File Name is for example "仔猫画像kitten_img.png")
   
2. Then dialog appeared, and Radio Button swith to "Material" or "Material and Object"
   
3. Output a following Error log
   

Code:

Internal Error
Version: 2.1.5
Window: dialog_blanket
Reason: badarg

Stack trace:
[{erlang,list_to_atom,
         [[20180,29483,30011,20687,107,105,116,116,101,110,95,105,109,103]],
         []},
{wpc_image,make_image_0,4,[{file,"wpc_image.erl"},{line,142}]},
{wpc_image,'-make_image/4-fun-0-',5,[{file,"wpc_image.erl"},{line,76}]},
{wings_dialog,event_handler,2,[{file,"wings_dialog.erl"},{line,506}]},
{wings_wm,handle_event,3,[{file,"wings_wm.erl"},{line,951}]},
{wings_wm,send_event,2,[{file,"wings_wm.erl"},{line,927}]},
{wings_wm,do_dispatch,2,[{file,"wings_wm.erl"},{line,824}]},
{wings_wm,dispatch_event,1,[{file,"wings_wm.erl"},{line,725}]},
{wings_wm,get_and_dispatch,0,[{file,"wings_wm.erl"},{line,646}]},
{wings,init,1,[{file,"wings.erl"},{line,147}]}]

Window dialog_blanket's crash handler got:
redraw

MacOSX 10.11.6
Wings3D 2.1.5