Use weak instead of unowned references

Fixes #495 and #496, thanks @via-guy.

InAppSettingsKit.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
 	s.name                  = 'InAppSettingsKit'
-	s.version               = '3.7.2'
+	s.version               = '3.7.3'
 	s.summary               = 'This iPhone framework allows settings to be in-app in addition to being in the Settings app.'
 
   s.description      = <<-DESC

Sources/InAppSettingsKit/include/IASKAppSettingsViewController.h

@@ -224,7 +224,7 @@ typedef NS_ENUM(NSUInteger, IASKValidationResult) {
 @interface IASKAppSettingsViewController : UITableViewController <IASKViewController, UITextFieldDelegate, MFMailComposeViewControllerDelegate>
 
 /// the delegate to customize IASK’s behavior. Propagated to child view controllers.
-@property (nonatomic, assign) IBOutlet id<IASKSettingsDelegate> delegate;
+@property (nonatomic, weak) IBOutlet id<IASKSettingsDelegate> delegate;
 
 /** base name of the settings plist file (default: `Root`)
  @discussion IASK automatically checks for specific or custom inApp plists according to this order (`DEVICE` being a placeholder for "iphone" on iPhone and "ipad" on iPad):

Sources/InAppSettingsKit/include/IASKMultipleValueSelection.h

@@ -22,7 +22,7 @@ NS_ASSUME_NONNULL_BEGIN
 /// This is used for PSMultiValueSpecifier and PSRadioGroupSpecifier
 @interface IASKMultipleValueSelection : NSObject
 
-@property (nullable, nonatomic, assign) UITableView *tableView;
+@property (nullable, nonatomic, weak) UITableView *tableView;
 @property (nonatomic, copy, readonly) NSIndexPath *checkedIndexPath;
 @property (nonatomic, strong) id<IASKSettingsStore> settingsStore;