Adds scaffolding for toggle spec tests.

- Uses a markdown file so I can have folding.
New failing test for foldable regions.

- It should fail now before the fold and implementation.
- This makes sure it lines up though. I'll want dj to be the next label
  at B1.
Working fold in spec test now.

- Test is legit.
Fixing package description.
Screen position code almost handling folded text.

- Labels and jumps before and after collapses.
- Can't jump to words on a collapsed line because you can't even
  navigate to them in Atom (always sends you to the beginning of line).
Only calculate font-size on jump once!

- I was recalculating the font size too many times.
Fetching config values only once.
Folding working.  Need to fix test though.
Restoring fold test with foldCurrentRow().

- This completes the code folding branch.
- Fixes #28.
:memo: Updates README.md and CHANGELOG.md.