icon-text for iconized LyX

[R. Lahaye]

Hi,

Currently, the LyX-window-title is also used as the
text for iconized LyX. This is quite inconvenient.

For example: if I'm working on "~/docs/myDocument.lyx",
it says in the window-title "LyX: ~/docs/myDocument.lyx".
When iconized, I only see underneath the icon "LyX: ~/doc"

I recommend to use for the iconized LyX only the basename
of the document-path without the "LyX:" prefix.

This way it is easier to recognize what active-document is iconized.
The LyX-prefix is also redundant because the LyX icon itself
is sufficient.

Thanks,
Rob.