Convert to gradle / Android Studio library project#2

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juanitobananas wants to merge 6 commits intobkhall:masterfrom

juanitobananas:dev

Commits on Mar 6, 2020

Convert to Android Studio / gradle project.
Juanito
committed
build.gradle: add google() repository.
Juanito
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Upgrade gradle plugin to 3.5.3 and gradle to 5.4.1.
Juanito
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AndroidManifest.xml: remove unnecessary SDK properties.
Juanito
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build.gradle: upgrade compileSdkVersion and targetSdkVersion to 29.
Juanito
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Version 1.0-1 (1).
Juanito
committed