Add AnalyticsScreenTimer and track more screens.

Update Analytics with new methods in MXAnalyticsDelegate.

Riot/Modules/GlobalSearch/Files/HomeFilesSearchViewController.h

@@ -17,6 +17,8 @@
 
 #import "MatrixKit.h"
 
+@class AnalyticsScreenTimer;
+
 /**
  `HomeFilesSearchViewController` displays the files search in user's rooms under a `HomeViewController` segment.
  */
@@ -27,4 +29,9 @@
  */
 @property (nonatomic, readonly) MXEvent *selectedEvent;
 
+/**
+ The screen timer used for analytics if they've been enabled. The default value is nil.
+ */
+@property (nonatomic) AnalyticsScreenTimer *screenTimer;
+
 @end