More freebsd support

This branch has a number of commits improving support for FreeBSD:
* limit table to processes only, excluding kernel threads (which didn't give any useful information anyway, it just appeared that processes were duplicated)
* support for additional fields, e.g. maj/minflt and c(s,u)time (like in the linux implementation) and onpro/numthr (like in the solaris implementation) and groups (like in the decosf implementation)
* fixed some previous merge/patch accidents wrt freebsd hint and readme files

Tested with a freebsd 8.0 (i386) and freebsd 9.0 (amd64) machine. Still works with a Linux machine.

Regards, Slaven