fix scroll position resetting on refresh

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

@@ -227,6 +227,11 @@ class ThreadActivity : SimpleActivity() {
                 ArrayList()
             }
 
+            messages.sortBy { it.date }
+            if (messages.size > MESSAGES_LIMIT) {
+                messages = ArrayList(messages.takeLast(MESSAGES_LIMIT))
+            }
+
             setupParticipants()
             setupAdapter()
 

app/src/main/kotlin/com/simplemobiletools/smsmessenger/helpers/Config.kt

@@ -3,7 +3,6 @@ package com.simplemobiletools.smsmessenger.helpers
 import android.content.Context
 import com.simplemobiletools.commons.helpers.BaseConfig
 import com.simplemobiletools.smsmessenger.models.Conversation
-import java.util.HashSet
 
 class Config(context: Context) : BaseConfig(context) {
     companion object {

app/src/main/kotlin/com/simplemobiletools/smsmessenger/models/ThreadDateTime.kt

@@ -1,3 +1,3 @@
 package com.simplemobiletools.smsmessenger.models
 
-open class ThreadDateTime(val date: Int, val simID: String) : ThreadItem()
+data class ThreadDateTime(val date: Int, val simID: String) : ThreadItem()