df9dfa145547529bf71afd4c6e8f3af947acaad0
This is what is needed to make Step (in KDE/kdeedu) build.
The rest of Eigen (outside of Sparse) is unaffected except for a few trivial changes that were needed.
calling this 2.0.3, will tag if no problem.
Question 1: why are *=scalar and /=scalar working right away ?
Same weirdness in DynamicSparseMatrix where operators += and -= work wihout
having to redefine them ???
That means a lot of features which were available for sparse matrices
via the dense (and super slow) implemention are no longer available.
All features which make sense for sparse matrices (aka can be implemented efficiently) will be
implemented soon, but don't expect to see an API as rich as for the dense path.
Other changes:
* no block(), row(), col() anymore.
* instead use .innerVector() to get a col or row vector of a matrix.
* .segment(), start(), end() will be back soon, not sure for block()
* faster cwise product
