Bug with malformed host in filter

[elof2 at sentor.se]

Hi Carter!

I stumbled on to a bug when accidentally executing a ra command with an 
incomplete IP address.
Strangely enough, the error-detection make different descisions depending 
of its place in the filter string.

Example:

#ra -Zb -nr argus.log - host 10.10.10.10 and host 10

pid 1907 (ra), uid 0: exited on signal 11 (core dumped)
host 10.10.10.10 and host 10 filter syntax error



The filter "tcp and host 10" and other elements before "host 10" also 
fail.

However, a filter of just "host 10" by itself does not fail, nor does 
"host 10 and host 10.10.10.10"


(ra version 3.0.6.2)

/Elof