fragment reassembly


we mostly need an on/off button
I even claim the need to turn it off is nonexistant

one option required, no-df
to allow fragments with the df bit set to enter the fragment cache
does not actually clear the df bit!

set reassemble (yes|no) [no-df]
on by default now - i. e. what you want (tm)

alternate reassembly methods removed
there is no need any more. really. full reassembly is fine.