Some unit test cases and stub methods implemented
Refactoring and cleanup code. Multiple methods added for simple, but dynamic mathematical operations
More convenient methods added to MathBinaryOperation and exception handling.
Merge https://github.com/Divendo/math-dragon

Assigning members to binary operations now is very awkward because you explictly need to specify the index number on each getter and setter. The next logical step is to derive MathOperationBinaryLinear from MathOperationBinary.
remove old class structure
Hover state implemented and MathBinaryOperationLinear derived from MathBinaryOperation
Ignoring IDE settings and setting the Android target back to 19.
+ .settings directory added to .gitignore (and deleted its contents from the repository)
* Changed the target to API 19
* Fixed a bug where MathBinaryOperator didn't initialise its child array

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