testing: Switch to Debian based guest images

Instead of extracting a downloaded Gentoo filesystem tree into a file
containing a reiserfs filesystem, create an ext3 filesystem inside a
sparse file, mount it and debootstrap an up-to-date Debian system. Use
this image as base for all UML guest images.

Also, drop support for the various consoles and use xterm
unconditionally.

testing/scripts/function.sh

@@ -55,13 +55,6 @@ function searchandreplace {
     [ -d "$DESTDIR" ] || die "$DESTDIR is not a directory!"
 
 
-    #########################
-    # create a temporary file
-    #
-
-    TMPFILE="/tmp/sr.$$"
-
-
     ###########################################
     # search and replace in each found file the
     # given string
@@ -69,17 +62,9 @@ function searchandreplace {
 
     for eachfoundfile in `find $DESTDIR -type f`
     do
-        sed -e "s/$SEARCHSTRING/$REPLACESTRING/g" "$eachfoundfile" > "$TMPFILE"
-        cp -f "$TMPFILE" "$eachfoundfile"
+        sed -i -e "s/$SEARCHSTRING/$REPLACESTRING/g" "$eachfoundfile"
     done
 
-
-    ###########################
-    # delete the temporary file
-    #
-
-    rm -f "$TMPFILE"
-
 }
 
 #############################################