Docs On Tap V2 4+

## Deleted Files
If a file is deleted from the Admin Portal, and a user tries to access it via a pre-existing file link, they will now be prevented from doing so.

## Adding Multiple Free Text Annotations
Previously adding subsequent free text annotations, after adding an initial free text annotation, took 3 clicks. We have reduced this to a single click to add each subsequent free text annotation.

## iPad Problem With Controls Being Hidden Behind Document
* We fixed a problem that caused the Page Controls (page number and left and right arrows), View Controls drop down and Zoom drop down to be hidden behind the document on the App installed on iPhone or iPad from the Apple App Store.
* We also took the opportunity to move the Page Controls (page number and left and right arrows) to the left hand side of the page to make them less obtrusive. We do still plan to reintroduce the page slider in the near future.

## iPad and Mac Memory Issues Causing Document To Reload
A number of users experienced a memory issue on some iPads and Mac computers that caused the document viewer to be reloaded. The result of reloading was that the page would momentarily be blank, then the viewer was initially displaying page 1 and then after a few seconds going back to the page that was previously being viewed. We found that the issue was most prevalent when scrolling through a large document using the "Continuous" Page Transition mode. We now default the Page Transition mode to "Page By Page" on iPad, iPhone and Mac devices. Users of these devices will receive a one-time message alerting them to this change. We will continue to investigate improving performance of the viewer so that the memory issues do not occur. However, it appears that those issues are related to the memory management of the Safari Webkit browser engine used by browser based applications on Apple devices. Research has shown that this is a known issue, not unique to Docs On Tap.