remove trailing whitespaces
remove redundant file exists check

TOCTOU

This check is already done when cmdline_parser try to open the file
Revert "Add authors to man page"

This reverts commit b5eb406f360e929684e498b707414b8ad79c16b8.

Apparently only OpenSSH puts authors on man pages
Update banner-grab Makefile for xalloc.o

We changed malloc to xalloc, except forgot to update the Makefile to
actually build and link against xalloc.o
Merge pull request #151 from ronnychevalier/rc/remove_redundant_check

Remove redundant file exists check
Merge pull request #147 from ronnychevalier/rc/trailing_whitespaces

Remove trailing whitespaces
Fix a segfault when udp->uh_ulen is less than 8
Merge pull request #155 from hmoore-r7/bug/udp-header-length

Fix a segfault when udp->uh_ulen is less than 8