add rows() and cols() calls
add Trace
on the lead of a Cache problem
change MVN for new implementation
add Eigen macro for small matrix memory alignment
add test showing new memory problems
simple test corresponding to previous commit, and issue #2
Revert "simple test corresponding to previous commit, and issue #2"

This reverts commit 0d4c930870e2a1ff5003a9044cf12763e4d0717e.
fix matrix product traits to match higher order product types
fix mat*mat*mat, relates #2
add Scalar cast
add some more tests
store all sub-expressions as value inside expressions, instead of const ref
add some comments