Broke up definition testing, added roadmap

The definition testing for matching + flashcards together didn’t allow
much flexibility for the matching interface. The new interface
leveraging tables gives more flexibility as we can now have column
headings and it keeps it nicely together.

Roadmap added giving a granular way forward for the project.
Merge branch 'master' of https://github.com/steveryb/selftestingmd

Conflicts:
	README.md