consolidate/hide parsing functions
cleanup Authority, remove ipLiteral note

Not attempting to compute ipLiteral due to the breadth of permitted values for
IPvFuture.

host          = IP-literal / IPv4address / reg-name
reg-name      = *( unreserved / pct-encoded / sub-delims )
IP-literal    = "[" ( IPv6address / IPvFuture  ) "]"
IPvFuture     = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
normalize Parameter's parameter names