added account_[set_]sipnat API functions

added ua_update_account API function
go directly to settings of new account
fixed some main activity layout bugs
keep main activity interactive when screen is locked
removed aor from UserAgent class
added register method to UserAgent class
added foregrounded and isDeviceLocked util functions
updated libbaresip distribution

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

@@ -93,7 +93,7 @@ class Account(val accp: String) {
 
         fun findUA(aor: String): UserAgent? {
             for (ua in MainActivity.uas) {
-                if (ua.aor == aor) return ua
+                if (ua.account.aor == aor) return ua
             }
             return null
         }
@@ -117,6 +117,8 @@ external fun account_auth_pass(acc: String): String
 external fun account_set_auth_pass(acc: String, pass: String): Int
 external fun account_outbound(acc: String, ix: Int): String
 external fun account_set_outbound(acc: String, ob: String, ix: Int): Int
+external fun account_sipnat(acc: String): String
+external fun account_set_sipnat(acc: String, sipnat: String): Int
 external fun account_audio_codec(acc: String, ix: Int): String
 external fun account_regint(acc: String): Int
 external fun account_set_regint(acc: String, regint: Int): Int