Merge branch 'compact-at-startup' into 'master'

...src/main/java/org/briarproject/bramble/api/StringMap.java

...va/org/briarproject/bramble/api/db/MigrationListener.java

.../briarproject/bramble/api/lifecycle/LifecycleManager.java

...est/java/org/briarproject/bramble/test/SettableClock.java

...n/java/org/briarproject/bramble/db/DatabaseConstants.java

...src/main/java/org/briarproject/bramble/db/H2Database.java

...in/java/org/briarproject/bramble/db/HyperSqlDatabase.java

...c/main/java/org/briarproject/bramble/db/JdbcDatabase.java

.../briarproject/bramble/lifecycle/LifecycleManagerImpl.java

...st/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

...riarproject/briar/android/login/OpenDatabaseActivity.java

briar-android/src/main/res/values/strings.xml