Half-assed file truncation

Need to do something with the page cache, but hopefully we won't mess
with it at all.
Adds some busybox editors

ed seems to work, not that I know it very well.  sed works too (at least
a basic sed 's/foo/bar/g' does).

vi doesn't work (screen control is all messed up).  Haven't tried awk.

You'll need to copy this config file to your busybox directory as
.config, then remake.  And of course copy the binary to KFS.

To save you all the hassle, I put symlinks in KFS for all the busybox
commands I use.

Here's some reading:
	http://linux.about.com/library/cmd/blcmdl1_ed.htm
	http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ed.html
	http://cm.bell-labs.com/cm/cs/who/dmr/qed.html