- all user interface unrelated data is now kept in baresip service

allowing proper recovery in case Android kills other activities
- many other improvements and bug fixes

app/src/main/kotlin/com/tutpro/baresip/Message.kt

@@ -1,7 +1,38 @@
 package com.tutpro.baresip
 
-import java.io.Serializable
+import java.io.*
+import java.util.ArrayList
 
 class Message(val aor: String, val peerUri: String, var direction: Int, val message: String,
               val timeStamp: Long, var new: Boolean): Serializable {
+
+    companion object {
+
+        val MESSAGE_HISTORY_SIZE = 100
+
+        fun messages(): ArrayList<Message> {
+            return BaresipService.messages
+        }
+
+        fun messages(messages: ArrayList<Message>) {
+            BaresipService.messages = messages
+        }
+
+        fun add(message: Message) {
+            BaresipService.messages.add(message)
+            var count = 0
+            var firstIndex = -1
+            for (i in BaresipService.messages.indices)
+                if (BaresipService.messages[i].aor == message.aor) {
+                    if (count == 0) firstIndex = i
+                    count++
+                    if (count > MESSAGE_HISTORY_SIZE) {
+                        break
+                    }
+                }
+            if (count > MESSAGE_HISTORY_SIZE)
+                BaresipService.messages.removeAt(firstIndex)
+        }
+
+    }
 }