Sparse Matrix/Vector refactoring with mostly return types changed. Thought that getSparcity was meaninful for SparseRealVector, and added a marker for SparseRealMatrix shape. Feel free to -1 either ;). I found an error in the unit tests, so will commit the changes there shortly, after a review.
commons/proper/math/trunk/src/java/org/apache/commons/math/linear/OpenMapRealMatrix.java