fix message syntax to use "habit.." or "habits.."

app/src/main/java/org/isoron/uhabits/commands/DeleteHabitsCommand.java

@@ -27,10 +27,12 @@ import java.util.List;
 public class DeleteHabitsCommand extends Command
 {
     private List<Habit> habits;
+    private Boolean plural;
 
     public DeleteHabitsCommand(List<Habit> habits)
     {
         this.habits = habits;
+        this.plural = habits.size > 1;
     }
 
     @Override
@@ -50,11 +52,21 @@ public class DeleteHabitsCommand extends Command
 
     public Integer getExecuteStringId()
     {
-        return R.string.toast_habit_deleted;
+        if (this.plural) {
+            return R.string.toast_habits_deleted;
+        }
+        else {
+            return R.string.toast_habit_deleted;
+        }
     }
 
     public Integer getUndoStringId()
     {
-        return R.string.toast_habit_restored;
+        if (this.plural) {
+            return R.string.toast_habits_restored;
+        }
+        else {
+            return R.string.toast_habit_restored;
+        }
     }
 }

app/src/main/res/values/strings.xml

@@ -31,14 +31,18 @@
     <string name="color_picker_default_title">Change color</string>
 
     <string name="toast_habit_created">Habit created.</string>
-    <string name="toast_habit_deleted">Habits deleted.</string>
+    <string name="toast_habit_deleted">Habit deleted.</string>
-    <string name="toast_habit_restored">Habits restored.</string>
+    <string name="toast_habits_deleted">Habits deleted.</string>
+    <string name="toast_habit_restored">Habit restored.</string>
+    <string name="toast_habits_restored">Habits restored.</string>
     <string name="toast_nothing_to_undo">Nothing to undo.</string>
     <string name="toast_nothing_to_redo">Nothing to redo.</string>
     <string name="toast_habit_changed">Habit changed.</string>
     <string name="toast_habit_changed_back">Habit changed back.</string>
-    <string name="toast_habit_archived">Habits archived.</string>
+    <string name="toast_habit_archived">Habit archived.</string>
-    <string name="toast_habit_unarchived">Habits unarchived.</string>
+    <string name="toast_habits_archived">Habits archived.</string>
+    <string name="toast_habit_unarchived">Habit unarchived.</string>
+    <string name="toast_habits_unarchived">Habits unarchived.</string>
 
     <string name="title_activity_show_habit" translatable="false"/>
     <string name="overview">Overview</string>