[boost] conversion review report

Hi Vicente, all,

Profuse apologies for the long delay in writing this report.  

Cheers,
Gordon

Report on Boost Conversion Library Review, August 20-29, 2011. 

I want to thank Vicente Botet Escriba for submitting the Conversion library for review and for his general
good nature in receiving criticism and alternate designs.

The Conversion library presents a general framework for plugging in conversion operations between
arbitrary types, providing a consistent interface for type-to-type conversions.  

The library is unfortunately rejected.  During the review, there were two votes for acceptance and two
against, and some interesting conversation from about a dozen participants.

The major reason the library can't be accepted in its current form is that there was near consensus that
there is no universal conversion domain, especially when the source or destination type might be a string.

Much of the review focused on possible One Definition Rule (ODR) violations, which are a consequence of
having a universal customization point using template specializations or function overloads.  Many
solutions were offered, which will make up the second part of this report, "How to Avoid Universality."

I. Concerns about the library

Conversions Are Not Generic?

While some reviewers didn't see the need for a generic conversion library (and I was a little surprised at