(thing-at-point-file-name-chars): Include non-ASCII

and use documented treatment of -.

lisp/thingatpt.el

@@ -193,9 +193,9 @@ a symbol as a valid THING."
 (put 'list 'end-op (function (lambda () (up-list 1))))
 (put 'list 'beginning-op 'backward-sexp)
 
-;;  Filenames and URLs
+;;  Filenames and URLs  www.com/foo%32bar
 
-(defvar thing-at-point-file-name-chars "~/A-Za-z0-9---_.${}#%,:"
+(defvar thing-at-point-file-name-chars "-~/[:alnum:]_.${}#%,:"
   "Characters allowable in filenames.")
 
 (put 'filename 'end-op