Android 11: work around r30 limitations for APK build

AndroidManifest.xml

@@ -27,6 +27,7 @@
     <application android:label="@string/app_name" android:icon="@drawable/icon"
 	    android:name=".APRSdroidApplication"
 	    android:usesCleartextTraffic="true"
+	    android:requestLegacyExternalStorage="true"
 	    android:allowBackup="true"
 	    android:theme="@style/DefaultTheme" >
 

build.gradle

@@ -81,7 +81,7 @@ android {
 	buildToolsVersion "29.0.3"
 	defaultConfig {
 		minSdkVersion 14
-		targetSdkVersion 30
+		targetSdkVersion 29
 		versionName "$build_revision"
 		versionCode versionCodeDate()
 		resValue "string", "build_revision", "$build_revision"

src/MapAct.scala

@@ -60,7 +60,7 @@ class MapAct extends MapActivity with MapMenuHelper {
 			setLongTitle(R.string.app_map, targetcall)
 		setKeepScreenOn()
 		setVolumeControls()
-		checkPermissions(Array(Manifest.permission.WRITE_EXTERNAL_STORAGE), RELOAD_MAP)
+		checkPermissions(Array(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE), RELOAD_MAP)
 		mapview.requestFocus()
 	}