New CLI tool & Relational metadata model

[YourMJK]

New CLI tool dreimetadaten

… with subcommands:

• migrate: Migrate previous JSON dataset to new relational database.
• export: Export dataset into various (more convenient) formats.
  • web: Export dataset for the web data directory.
• webbuild: Generate HTML code for the web page using a template file.

Replaces previous tools D3F-MetadataExporter, D3F-WebGenerator (and its companion script webBuild.sh) which are moved into code/_legacy/.

Relational metadata model

A new relational model (MetadataObjectModel.swift) which aims to properly capture all the correct data, attributions and relationships without redundancies in preparation for – and with a direct mapping to – a proper SQL database (#14).

Incomplete list of notable changes:

• Table for "person"
• Attributions for "autor", "hörspielskriptautor", "sprecher", "pseudonym" and "rolle" by ID (not string) with N:M relations for former three (i.e. referencing multiple "person" is possible)
• Table for "medium" (CD) and not using "teile" for media that doesn't narratively partition a "hörspiel" anymore.
• A "hörspiel" is strictly made up of "kapitel" which reference a single "track" on a "medium"