Cleanup makefile, implement set_hdr field.

Makefile modified so the printing is similar to the kernel build
output.  This keeps it legible for long command lines.  Use V=1
to enable verbose output.
Add debug, ensure test objs cleaned up, add some tests.

Debug symbols should be added by default for now.  The clean target
wasn't clearing objects in the tests directory.  Add a few test
details for the RtpPacket class.