[boost] [multi_index] scope_guard

Hi Joaquín, I'm looking at your version of scope_guard in the current CVS. I'm intersted to know why you didn't include boostified versions of the macros ON_BLOCK_EXIT from Andrei and Petru's original article. Was it just because you didn't need it or because you found it objectionable for some reason? Also, I read that you were disappointed with its performance, and I see that you only use it for checking invariants, when enabled. Do you plan on keeping it in Boost.MultiIndex? Have you considered submitting it for fast track review? Jonathan