Update .gitignore & checkout some IDEA files

.gitignore

@@ -1,9 +1,29 @@
+## Android Studio ##
 *.iml
-/.idea
+# We ignore everything from the IDE, except non user specific things
+/.idea/*
+# Auto-import exclusion list (Editor -> General -> Auto Import)
+!.idea/codeInsightSettings.xml
+# Code style setup (Editor -> Code Style)
+!.idea/codeStyles/
+# Detekt plugin configuration (Tools -> Detekt)
+!.idea/detekt.xml
+# Required plugins (Build, Execution, Deployment -> Required Plugins)
+!.idea/externalDependencies.xml
+# File and code templates and their metadata (Editor -> File and Code Templates)
+!.idea/fileTemplates/
+!.idea/file.template.settings.xml
+# Project icon
+!.idea/icon.svg
+# Code inspections setup (Editor -> Inspections)
+!.idea/inspectionProfiles/
+# Version control system metadata
+!.idea/vcs.xml
+
+# Gradle
 .gradle
+build
 /local.properties
+
+# macOS
 .DS_Store
-/build
-/captures
-.externalNativeBuild
-.cxx