[eigen] Special topic page on Aliasing

[Jitse Niesen <jitse@xxxxxxxxxxxxxxxxx>]

Hello,

I started a special topic page on Aliasing; you can see the start at

   http://eigen.tuxfamily.org/dox-devel/TopicAliasing.html

My idea is to explain aliasing from a user's perspective, and mention 
as little about the internals of Eigen as possible.

However, I'm now wondering whether we need this page. There is quite a bit 
of overlap with the page "Lazy Evaluation and Aliasing" at

   http://eigen.tuxfamily.org/dox-devel/TopicLazyEvaluation.html

In my mind the main topic of that page is lazy evaluation. Perhaps the 
need to learn about lazy evaluation is a bit less immediate for the user 
(that's why I very immodestly bumbed 'my' aliasing page to the above the 
lazy evaluation page in the Overview page).

I think that the pages are sufficiently different that it's useful to have 
both, but I want to give others a chance to comment first before I do more 
work on the aliasing page.

Cheers,
Jitse