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