Remove superseded SelectionMover class

The SelectionMover class has been superseded by more flexible combinations of filters, scanners and utils. The replacements bring less dependence on the cursor node for positioning, allowing greater flexibility and re-use.

Removing this code and associated tests performs the final step necessary to close #224. In addition, this eliminates redundant line detection logic, so #225 is also closed by this as well.
Being able to use `hasOwnProperty` in the implementation is nice, but in the API of `BlacklistNamespaceNodeFilter` it seems strange to use a map with those dummy boolean values, looking at the code constructing the object one wonders what the `true` means there. I would prefer an array instead, `indexOf` might not be a performance problem (perhaps even faster, untested claim), and also not much harder to get when reading the code of `acceptNode`.