Merge branch 'Issue1' into 'master'

.gitignore

app/.gitignore

app/build.gradle

app/proguard-rules.pro

...va/com/example/a8_bitinvader/ExampleInstrumentedTest.java

app/src/main/AndroidManifest.xml

app/src/main/java/com/example/a8_bitinvader/Background.java

app/src/main/java/com/example/a8_bitinvader/Bullet.java

app/src/main/java/com/example/a8_bitinvader/Enemy.java

...src/main/java/com/example/a8_bitinvader/GameActivity.java

app/src/main/java/com/example/a8_bitinvader/GameView.java

app/src/main/java/com/example/a8_bitinvader/Joystick.java

...src/main/java/com/example/a8_bitinvader/MainActivity.java

app/src/main/java/com/example/a8_bitinvader/Player.java

app/src/main/java/com/example/a8_bitinvader/PopUpWindow.java

...n/java/com/example/a8_bitinvader/ReverseInterpolator.java

app/src/main/java/com/example/a8_bitinvader/Sprite.java

...src/main/java/com/example/a8_bitinvader/TestPositive.java

app/src/main/res/anim/blink_animation.xml

app/src/main/res/anim/fade_animation.xml