Don't do file-read progress bar updates with a timeout; instead, update

Don't do file-read progress bar updates with a timeout; instead, update
the progress bar up to 100 times, as we get another percent closer to
completion.  That reduces the number of times we run the GTK+ main loop;
that main loop may do a "select()" or "poll()" or FIONREAD "ioctl" to
check for input from the X server, adding to the CPU overhead of reading
a file.

The packet filtering progress bar is already updated in a similar
fashion; make it also do up to 100 updates.

svn path=/trunk/; revision=597