I'd expect the portnum component to remain uninitialized in case the
given URI specifies no port number -- however, decompose_uri() raises an
error instead. Will address this in a subsequent commit.
This also installs symlinks from "zeek" and "bro-config" to a wrapper
script that prints a deprecation warning.
The btests pass, but this is still WIP. broctl renaming is still
missing.
#239
