all: spelling inconsistency for networking terms

[mikioh]

Some packages use hostname and others host name. The worst is the net package which uses both. It might be better to align to host name defined in https://tools.ietf.org/html/rfc7719.

Host name: This term and its equivalent, "hostname", have been
widely used but are not defined in [RFC1034], [RFC1035], [RFC1123], or [RFC2181]. 

[as]

Where is host name defined in RFC 7791?

https://tools.ietf.org/html/rfc7791

[mikioh]

s/7791/7719/g

[quentinmit]

I would instead encourage us to avoid the term "hostname" unless it specifically refers to the operating system's notion of hostname. (As RFC 7719 mentions, the hostname often does not include the domain part.)

[mikioh]

@mdempsky tackled this issue a bit for Lookup functions and used the term host for host names, the term name for domain names in CL 34650; just FYI.

[gopherbot]

CL https://golang.org/cl/34875 mentions this issue.

[gopherbot]

CL https://golang.org/cl/34876 mentions this issue.

[gopherbot]

CL https://golang.org/cl/34879 mentions this issue.