Initial attempt at pretty-printing failures.

Right now it prints results like this:

     Expected: 1
          got: [2
      3
      4] (using =)

But I want to change -to-s to take an indentation-chars argument that specifies just how long each line *after the first one* should be indented. (A function that indents a string thusly is easy to imagine.) This way you get results like this:

     Expected: 1
          got: [2
                3
                4] (using =)

It's too fragile to just change -to-s to take a number arg, because if you change the string, you have to change the number too, and it has to be correct:

(-fail (str "Expected: " (-to-s 10 expected#) speclj.platform/endl "     got: " (-to-s 10 actual#) " (using =)"))

An alternative is to change -fail to take strings directly, and it can calculate the length of the first string arg to get the indentation-char-count:

(-fail "Expected: " (eventually-to-s expected#) speclj.platform/endl "     got: " (eventually-to-s actual#) " (using =)")

Then we only need to return something from `eventually-to-s` that -fail can recognize as something that needs to be converted with `(-to-s indent-char-count the-string)`. It probably suffices to just return `{:-to-s true :str str}`

Kind of ugly, but it requires the fewest changes to the codebase to get the above indentation working.

Thoughts?