Don't use tcp.c tcp.h any more.

Nor do we need openssl or math libraries.
But I did have to keep 4 little routines from tcp.c,
dealing with name ip dot conversions.
They are now in stringfile.c.
These are ipv4 specific, and I need to write ipv6 versions.
Next push will probably delete tcp.c, once I'm sure I don't need it any more.