remove some stray files

.gitignore supercedes .cvsignore. The uuencoded test file is of no use
since commit acd66de.
update URLs in the README

The anonymous CVS server isn't functional any more. The LBL URL has
changed. Current version of tcpslice is now on GitHub.
nflog - minor changes
NFLOG: more minor improvements

Reduce pointer conversion and do version check before header decoding.
NFLOG: fix error message