Deprecated five lilypondfiletools block classes.

These block classes are deprecated; they are trivial wrappers around Block:

    lilypondfiletools.BookBlock
    lilypondfiletools.BookpartBlock
    lilypondfiletools.HeaderBlock
    lilypondfiletools.MIDIBlock
    lilypondfiletools.PaperBlock

These block classes will remain; they implement special formatting logic:

    lilypondfiletools.ContextBlock
    lilypondfiletools.LayoutBlock
    lilypondfiletools.ScoreBlock