replace &*i, (&*i) + 1 with an explicit tmp; not sure what that is needed, but vs 2k13 seems to barf (bad code) otehrwise, and I'm not sure they are wrong. Easier to write with temp and not worht digging into now)
Added docs for Bijection<>::As<> - and impl for Bijeciton<>::Inverse
cleanup small signed/unsigned issues with streams/overflow