Fix to share feature

Under the cover revision

* Added back button

* Fixed minor problems with iOS13

* Updated for compatibility with iOS 10 and above.
* Improved usability and sharing.

* Improved navigation
* Bug fixes
* Search term highlighting

iOS6 and iPhone 5
The app now supports iOS6 and also the new screen size on the iPhone 5.

Printing
Now you can print a single calculator or the whole calculator tape to any AirPrint printer.

Improved Email
In addition to the standard email, you may now send any calculator or the whole calculator tape as a PDF file attached to an email.

Improved Navigation
Favorites can now also show the list of your most used calculators and those most recently used.

* Completely updated for retina displayed with high resolution graphics
* Now with 15 aviation calculators - both standalone and integrated with content
* Improved interface for better readability
* Email any page
* Built-in calculator.

* Improved memory management and bug fixes

* Fixed issue of text hidden by images on pages 552 and 553.

* Now supports iPad as well as iPhone and iPod Touch
* New higher resolution graphics
* Improved navigation and search