Import howett.net/plist by its correct name

Also bumping the version to one with a go.mod.

vendor/howett.net/plist/zerocopy.go

@@ -0,0 +1,20 @@
+// +build !appengine
+
+package plist
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+func zeroCopy8BitString(buf []byte, off int, len int) string {
+	if len == 0 {
+		return ""
+	}
+
+	var s string
+	hdr := (*reflect.StringHeader)(unsafe.Pointer(&s))
+	hdr.Data = uintptr(unsafe.Pointer(&buf[off]))
+	hdr.Len = len
+	return s
+}