* Rewrite the triangular solver so that we can take advantage of our efficient matrix-vector products:
    => up to 6 times faster !
* Added DirectAccessBit to Part
* Added an exemple of a cwise operator
* Renamed perpendicular() => someOrthogonal() (geometry module)
* Fix a weired bug in ei_constant_functor: the default copy constructor did not copy
  the imaginary part when the single member of the class is a complex...