Add vector-wise normalized and normalize functions

Submitted by Gael Guennebaud @ggael

Assigned to Nobody

Link to original bugzilla bug (#562)

Description

Everything is in the title, we need to be able to do things like:

a.colwise().normalize();
b = a.rowwise().normalized();

which are very frequent. See for instance http://forum.kde.org/viewtopic.php?f=74&t=95000.

Blocking

#387 (closed)