Adding upstream version 3.6.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

writer.go

@@ -0,0 +1,13 @@
+package mailyak
+
+import "bytes"
+
+// BodyPart is a buffer holding the contents of an email MIME part.
+type BodyPart struct{ bytes.Buffer }
+
+// Set accepts a string s as the contents of a BodyPart, replacing any existing
+// data.
+func (w *BodyPart) Set(s string) {
+	w.Reset()
+	w.WriteString(s)
+}