fix(lib): enable multiple consecutive slash support

Closes #754
Closes #808
Closes #815

Apparently more applications use multiple slashes in a row than I
thought. There is no easy way around this other than to do this hacky
fix to avoid net/http#ServeMux's URL cleaning.

test/cmd/httpdebug/main.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"log/slog"
+	"net/http"
+)
+
+var (
+	bind = flag.String("bind", ":3923", "TCP port to bind to")
+)
+
+func main() {
+	flag.Parse()
+
+	slog.Info("listening", "url", "http://localhost"+*bind)
+	log.Fatal(http.ListenAndServe(*bind, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		slog.Info("got request", "method", r.Method, "path", r.RequestURI)
+
+		fmt.Fprintln(w, r.Method, r.RequestURI)
+		r.Header.Write(w)
+	})))
+}