Added a name column to the formula database

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Added tabs to the operation source drawer

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Created a dimensions file for different screen sizes.
So the keyboard is now also displayed correctly on smaller screens.

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Fixed a bug where MathOperationFunction wouldn't be saved properly to XML

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Improved tablet layout

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>
Created a keyboard layout for landscape mode and enhanced the layout of the keyboard for tablets
* Fixes #40

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>