Version 4.2 (built on 18.10.30)
Includes fix to avoid deadlock situation with WatchdogMonitor which could result in USB communication errors. （修复看门狗在出现死锁状态时可能导致的USB通讯错误。）
注：死锁指两个或两个以上的进程在执行过程中，由于竞争资源或者由于彼此通信而造成的一种阻塞的现象，若无外力作用，它们都将无法推进下去。
- Comm error appeared to require that user disconnect USB cable and restart the Robot Controller app to recover.
- robotControllerLog.txt would have error messages that included the words "E RobotCore: lynx xmit lock: #### abandoning lock:"
Includes fix to correctly list the parent module（直接与手机相连的REV模块为主模块） address for a REV Robotics Expansion Hub in a configuration (.xml) file.
- Bug in versions 4.0 and 4.1 would incorrect list the address module for a parent REV Robotics device as "1".
- If the parent module had a higher address value than the daisy-chained（子模块） module, then this bug would prevent the Robot Controller from communicating with the downstream Expansion Hub.
Added requirement for ACCESS_COARSE_LOCATION（ACCESS_COARSE_LOCATION是APP的一项权限请求） to allow a Driver Station running Android Oreo to scan for Wi-Fi Direct devices.
Added google() repo（repo就是repository，容器，即一个下载第三方代码库的地方） to build.gradle because aapt2 must be downloaded from the google() repository beginning with version 3.2 of the Android Gradle Plugin.
注：以前在打开ftc_app项目首次build的时候可能会出现“Error: java.util.concurrent.ExecutionException: com.android.builder.internal.aapt.v2.Aapt2Exception: AAPT2 error: check logs for details”的报错。这是没有下载aapt2导致的，以后如果你的Android Studio上没有aapt2，gradle就会自动下载。
- Important Note: Android Studio users will need to be connected to the Internet the first time build the ftc_app project.
- Internet connectivity is required for the first build so the appropriate files can be downloaded from the Google repository.
- Users should not need to be connected to the Internet for subsequent builds.
- This should also fix buid issue where Android Studio would complain that it "Could not find com.android.tools.lint:lint-gradle:26.1.4" (or similar).
Added support for REV Spark Mini motor controller as part of the configuration menu for a servo/PWM port on the REV Expansion Hub.
Provide examples for playing audio files in an Op Mode.（终于可以在机器人上放凉凉了）
Block Development Tool Changes
- Includes a fix for a problem with the Velocity blocks that were reported in the FTC Technology forum (Blocks Programming subforum).
- Change the "Save completed successfully." message to a white color so it will contrast with a green background.
- Fixed the "Download image" feature so it will work if there are text blocks in the op mode.
Introduce support for Google's TensorFlow Lite（精简版） technology for object detetion for 2018-2019 game.（开始支持AI视觉识别）
注：经过测试，使用高通615 SOC的坚果手机和高通410 SOC的华为G7在调用TensorFlow的时候都提示Sorry!This device is not compatible with TFOD 。高通835 SOC的小米6测试通过。
- TensorFlow lite can recognize Gold Mineral and Silver Mineral from 2018-2019 game.
- Example Java and Block op modes are included to show how to determine the relative position of the gold block (left, center, right).
