Update the comments on if_alloc(), if_free(), if_free_type(), and if_attach.
Update the comments on if_alloc(), if_free(), if_free_type(), and
if_attach.

Remove a comment about pre-3.0 network drivers from if_attach().

Be a bit more consistant about whitespace near comments.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase