Refactor init.go

Original Author: @dkirillov

Goals for refactoring `init.go` are:
- decouple or provide flexibility in the init to support different render/backend combos.
- maintain or improve code coverage for `init.go` (84% last known) and any new files.

Look through comments for #136 for some ideas.

Start by reading init.go and the discussion referenced in #136. Map how initialization currently couples render and backend choices, then inspect the existing coverage for init.go. Done means different render/backend combinations are supported without reducing the known 84% coverage, with any new files covered as well.

Written by the indexing model from the issue text.