PluginsRegister 不再对外暴露，需要手动注册插件请使用  FlutterBoost.instance().engineProvider().getPlugins().add(new FlutterPlugin());

add analysis_options.yaml and fix error

支持Hero动画

如何设置页面横屏

# Conflicts:
#	android/build.gradle
#	android/src/main/java/com/idlefish/flutterboost/Platform.java

remove useless code in boost_page_route

-  boost_page_route_test.dart
test `of` and `tryOf` method

- Remove overridden buildTransitions method because it seems useless.

- Also removed Stub, didn't find it used.

[sync] 2020/2/20

[sync] 2020/2/20

add travis url

# Conflicts:
#	android/build.gradle
#	android/src/main/java/com/idlefish/flutterboost/Platform.java
#	example/android/app/build.gradle
#	ios/Classes/Boost/FlutterBoostPlugin.h
#	ios/Classes/Engine/FLBFlutterEngine.m
#	lib/flutter_boost.dart