README.md: Seneval misc. improvements.
README.md: Seneval misc. improvements.

- Note that the blog post is several years old, but still accurate.

- Expand comments in example.

- Mention test name suffixes in Filtering By Name. (The section
  on test name suffixes still needs to be added.)

- Note that compiling out `FAIL_WITH_LONGJMP` can save several
  hundred bytes of memory, since `jump_buf`s can be large.

- Add `-a` to section about CLI test runner arguments.

silentbicycle/greatest,silentbicycle/greatest