Merge branch '15-improve-build-process' into 'master'

.gitlab-ci.yml

android/.gitignore

android/app/build.gradle

android/app/src/debug/AndroidManifest.xml

android/app/src/main/AndroidManifest.xml

.../main/java/org/benoitharrault/midisynth/MainActivity.java

.../main/kotlin/org/benoitharrault/midisynth/MainActivity.kt

android/app/src/profile/AndroidManifest.xml

android/build.gradle

android/gradle.properties

android/gradle/wrapper/gradle-wrapper.properties

android/settings.gradle

fastlane/metadata/android/en-US/changelogs/12.txt

fastlane/metadata/android/fr-FR/changelogs/12.txt

pubspec.yaml