Scrub "evaporator" code

[malachib]

Scattered everywhere are EBO implementations.

"Evaporator" paradigm was an attempt to consolidate that. Showed promise, but now code is crusty.

This issue also covers code that doesn't participate in evaporator paradigm, but is a candidate for such

Consider something like estd::ebo namespace

Factor in discoveries made in embr::gl ebo code

Use cases:

• Primary: Given class T:
  • If empty, ebo it with something like a T value accessor
  • If not empty, use something like a T& value accessor