Consider Boost.Compute's Eigen Interop

[RobertLeahy]

See documentation here (pretty sparse at the moment) and code here and here.

Could eliminate the need for the boost_compute_detail_type_name_trait.hpp header/workaround/hack, but we'll have to evaluate how Boost.Compute integrates with Eigen versus how we're doing it (it aliases Eigen::Matrix4f to float16, for example, which doesn't seem like something we'd want since float16 doesn't (as far as I know) have matrix semantics).