Supporting newer android versions, API technikal upgrades

This update from Apple will improve the functionality of this app. No new features are included.

- Minor fixes and improvements.

IOS7 improvements and bug fixes.

- IOS6 optimizations.
- Minor fixes.
- Spelling correction in Italian.

IOS5 optimizations.
Spelling correction in English.

- Minor fixes and improvements.
- Correction of the word "Falsch" in German.

- Added visualization of times tables for learning.
- Enabled return to the junior / senior option.
- Improved graphics.
- Minor fixes.

- High resolution graphics for Retina Display
- Optimizations and minor fixes

Addition of translations in English, French, German, Spanish and Italian.