Naming, layout and comments: descriptive full-word names, one item per line in wrapped calls and literals, and doc comments on exported names

Short and single-letter names in application code become full words (tests
keep theirs). Wrapped calls, signatures and composite literals put one item
per line, and one-line function bodies are expanded. Exported names and
groups of constants get doc comments, and comments refer to the renamed
identifiers.

internal/middleware/real_ip_test.go

@@ -12,7 +12,9 @@ import (
 func serveRealIP(t *testing.T, opts RealIPOptions, peer string, h map[string]string) ClientInfo {
 	t.Helper()
 	var got ClientInfo
-	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { got = Client(r) })
+	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		got = Client(r)
+	})
 	req := httptest.NewRequest("GET", "/", nil)
 	req.RemoteAddr = peer
 	for k, v := range h {