DenseSparseMatrix is now column-major.

1. Introduce new typdefs in eigen.h to allow for column
   major matrices.

2. Clean up old unused typedefs, and the aligned typedefs
   since they do not actually add any real performance.

3. Made eigen.h conform to the google style guide by removing
   the using directives. They were polluting the ceres namespace.

4. Made the template specialization generator work again.

Change-Id: Ic2268c784534b737ebd6e1a043e2a327adaeca37