Remove support for Dot.

It was cool, but it's impractical for anything big. Also, I want to
write tests, and I don't want to have to write tests for the dot code
too. If you need dot then use github.com/eaburns/pp.
Change pretty.Print to pretty.Fprint, add pretty.Print.

This makes it consistent with fmt, and it will shut up go vet. Plus,
most of the times when I used pretty.Print I was just printing to
os.Stdout anyway. It's a popular output file.
Add gok.sh.
Don't add \n to structs without exported fields. Add … to indicate unexported fields.

Fixes #2.
No space between struct name and {.
Allow the indentation to be changed.

Fixes #4.
Support map types.

Fixes #1.
Declare example types within their Example functions where possible.
Add some tests.

It's strange to use Examples for testing, but it works well in the
case of this package, so I ran with it.
Tiny test name change.
Update godoc comments.
Merge pull request #6 from eaburns/dev/eaburns

Various fixes.