reimplemented AbstractVector.subtract(Vector,Factory)
corrects a typing error
Merge pull request #47 from ewaldgrusk/fix_abstractvector_subtract

Fixes a bug in AbstractVector.subtract(Vector, Factory)
added credits for Ewald
issue #18: rotation included for Basic2DMatrix. Also created test method
improved javadoc
Use Matrix.equal() and predefined correct matrix for testing on correctness
rename test method to testRotate_2x2
use i and j variables as loops counters
The result matrix should be created with given factory
implemented rotation in abstractmatrix
cleanup
include rotate(Factory factory)
cleanup
delete redundant functions, add test cases for other dimensions
removed duplicate function for rotation, edited spaces
spaces
Merge pull request #48 from jakobmoellers/master

fixes issue #18
added credits for Jakob; cleared code a bit
updated README