Refactoring floating view opening/closing logic

> Creating a base view for floating panels with some common methods
> Moving the getOpen method to individual classes
> Moving the folder icon animation logic to folder icon
> Moving all the logic related for opening folder to Folder class

Change-Id: I898dfb6870b857cb921d2729b89618bc43ff2e88
diff --git a/res/values/config.xml b/res/values/config.xml
index a942f02..5b3ee46 100644
--- a/res/values/config.xml
+++ b/res/values/config.xml
@@ -91,6 +91,9 @@
     <!-- View ID used by cell layout to jail its content -->
     <item type="id" name="cell_layout_jail_id" />
 
+    <!-- View ID used by PreviewImageView to cache its instance -->
+    <item type="id" name="preview_image_id" />
+
 <!-- Deep shortcuts -->
     <integer name="config_deepShortcutOpenDuration">220</integer>
     <integer name="config_deepShortcutArrowOpenDuration">80</integer>