Squashed 'src/github.com/vrischmann/rdbtools/' changes from ba01d60..a46c7a8

a46c7a8 Migrate Parser to an interface
1d8ba9e Move the metadata types into their respective files
6129c01 Add some documentation

git-subtree-dir: src/github.com/vrischmann/rdbtools
git-subtree-split: a46c7a8616d7495e9054dd419eda4362274c6f66
Merge commit '139b0efd307abd12b2ea237f2d33037d4ead41cf'