Cleanup base directory selection, use Context.getExternalFilesDirs and request WRITE_EXTERNAL_STORAGE permission, use AndroidX and raise minSdkVersion to 14. Use File instead of plain Strings for paths in some places, use try-with-resources, and some other small improvements.

brouter-server/src/main/java/btools/server/RouteServer.java

@@ -294,7 +294,7 @@ public class RouteServer extends Thread implements Comparable<RouteServer>
         }
 
         ServiceContext serviceContext = new ServiceContext();
-        serviceContext.segmentDir = args[0];
+        serviceContext.segmentDir = new File ( args[0] );
         serviceContext.profileDir = args[1];
         System.setProperty( "profileBaseDir", serviceContext.profileDir );
         String dirs = args[2];