remove the FIXEDMAP flag from tests/examples
Merge pull request #16 from bmatsuo/no-fixedmap

remove the FIXEDMAP flag from tests/examples
organize godoc and point to C documentation

- move top-level godoc to a new file, mdb.go
- add an introduction that points to the C docs
add a short (godoc embedded) example based on tests
Merge pull request #19 from bmatsuo/docs

Docs