Coordinating the Hadrian merge

Hi Andrey and Alp, Before ICFP we concluded that we will merge Hadrian into the GHC tree. This unfortunately took a back-seat priority-wise while I sorted out various release things but I think we are now in a position to make this happen. Andrey, would you be okay with my merging Hadrian as-is into the GHC tree? In the past we discussed squashing the project's early history however I've had very little luck doing this cleanly (primarily due to the difficulty of rebasing in the presence of merge commits) After merging there will be a period where we flush the pull request queue but I don't anticipate this causing much trouble. Cheers, - Ben