these are some changes to the system so that Travis-CI.org can work; mostly this is about getting paths
to custom versions of tcpdump (in 32-bit and 64-bit, target and host) working right.
added some text pointing at community
when running tests or compiling, do not stop if there is an error, but accumulate it for later (questionable)
set the debug on the new node earlier
the rpl_node constructors need to set self=false consistently