Further improvements to httphi API (#173)

* add Exchange.WriteBodyString

* Mux.MaxPathValues and other improvements

* Mux PathValue improvemnt and fixes

* MuxSlice more method muxing improvements

* diagram out interesting approach to form parsing for clanker

* refactor RequestParseForm and achieve greatness in API design

* explicit naming of headerCapacityKV value in kvBuffer.Reset

* fix Mux bug not matching paths correctly; httpraw HTTP V1 naming applied

* rename many examples,use httphi in examples,remove useless maxAwaitingConn field

* add ipv4.String

* add ipv4 UnspecifiedAddr and BroadcastAddr

* add ethernet.String

ethernet/definitions.go

@@ -25,6 +25,15 @@ const (
 	MinimumMTU = MinimumFrameLength - sizeHeaderNoVLAN
 )
 
+// String returns the colon-separated hexadecimal text representation of a hardware address.
+func String(hwAddr [6]byte) string {
+	// See net/netip's (Addr).string4 pattern.
+	var buf [maxAddrStringLen]byte
+	return string(AppendAddr(buf[:0], hwAddr))
+}
+
+const maxAddrStringLen = len("ff:ff:ff:ff:ff:ff")
+
 // AppendAddr appends the text representation of the hardware address to the destination buffer.
 func AppendAddr(dst []byte, hwAddr [6]byte) []byte {
 	for i, b := range hwAddr {