[boost] [Hana] Formal review dates

Dear Boost, As I already announced in a previous message, a formal review is about to be asked for Hana. The current preferred dates would be April 25 - May 8. However, we are concerned that people might be unavailable to do reviews such a short time before C++Now. The goal of this message is to ask potential reviewers whether they would be available during the proposed period. If people seem unfavorable or if there is too little feedback to this message, we will consider pushing back the review to after C++Now. Note that one reason why I'm trying to squeeze the review before C++Now is because it could hugely help with marketing the library if it was accepted. Regards, Louis