handle sending group SMS

- in Context.getMessages, split the sender number by spaces " " to get each contact.
- apply update in the android-smsmms lib - do not pass threadId in Transaction.sendNewMessage

app/src/main/kotlin/com/simplemobiletools/smsmessenger/activities/ThreadActivity.kt

@@ -829,7 +829,7 @@ class ThreadActivity : SimpleActivity() {
             transaction.setExplicitBroadcastForDeliveredSms(deliveredIntent)
 
             refreshedSinceSent = false
-            transaction.sendNewMessage(message, threadId)
+            transaction.sendNewMessage(message)
             thread_type_message.setText("")
             attachmentSelections.clear()
             thread_attachments_holder.beGone()