Filter out control characters in shell buffer or copy from shell buffer

[David Aspinall]

Any idea how I can get rid of the characters such as Ú that appear in the Isabelle shell buffer? XEmacs doesn't display them, but they appear if printed or pasted into other text files.

+++    ~(c_BT_Obt_OLf t_a = c_BT_Obt_OLf t_a)Û
Ú+++ INFERENCE: Equality
+++ {lit = ~(c_BT_Obt_OLf t_a = c_BT_Oreflect t_a (c_BT_Obt_OLf t_a)),
+++  path = [1], res = c_BT_Obt_OLf t_a, lr = true, thm = |- F}Û
Ú+++   isa th: "False"  [.]Û
Ú+++ fol_term_to_hol: c_BT_Obt_OLf t_a = c_BT_Oreflect t_a (c_BT_Obt_OLf t_a)Û
Ú+++   result type: boolÛ
Ú