Add sleep tracking, statistics module and backup features

Features:
- Sleep tracking with timer and manual duration input
- Statistics module with 5 tabs (daily summary, feeding, diapers, sleep, growth)
- Export/Import backup functionality in settings
- Complete German, French and Italian translations

app/src/main/java/utils/NumericUtils.kt

@@ -81,7 +81,8 @@ class NumericUtils (val context: Context) {
                     LunaEvent.TYPE_TEMPERATURE -> measurement_unit_temperature_base
                     LunaEvent.TYPE_BREASTFEEDING_LEFT_NIPPLE,
                     LunaEvent.TYPE_BREASTFEEDING_BOTH_NIPPLE,
-                    LunaEvent.TYPE_BREASTFEEDING_RIGHT_NIPPLE ->
+                    LunaEvent.TYPE_BREASTFEEDING_RIGHT_NIPPLE,
+                    LunaEvent.TYPE_SLEEP ->
                         context.getString(R.string.measurement_unit_time_minutes)
                     else -> ""
                 }