v1.2.0 - export packs for The Choicer Voicer

DubForge can now build packs for The Choicer Voicer as well as for DubStage.
Pick the target format at the top of the window; the interface adapts to it.

Added

• Two export formats. DubStage as before, or The Choicer Voicer. The CV
  profile adds a character per clip, an image per character and the pack
  description. The DubStage profile is unchanged.

• Choicer Voicer export: one .txt per line beside its audio, plus
  _pack_info.ini, and the video as OGV — Godot reads nothing else, so a pack
  without dub_video.ogv will not load at all.

• Character images straight from the scene. Select a clip, type the
  character, press "Grab image": a still frame is pulled from the video at that
  moment and assigned to that character, with a thumbnail next to the field. The
  pack icon works the same way. Real packs use one image per speaker rather than
  one per line, and the export follows that.

• Numbering runs per character in the CV profile, not across the scene —
  06_woody may sit later than 06_buzz. Order within the scene comes from the
  timestamps alone, which is how the game reads it.

About the format

The .txt format is documented nowhere; the official route is the editor inside
the game. This implementation was read out of a working pack and checked against
it — all twenty metadata files and the _pack_info.ini of that pack are
reproduced byte for byte. UTF-8, CRLF, no newline at the end, timestamps padded
to two digits with three decimals, lists without a space after the comma.

Captions never need escaping because real packs use typographic quotation marks
inside the straight ones. The export does the same, so the question of how the
game escapes a " never comes up.

Upgrading

The update banner in either tool will offer it. Packs, recordings and settings
are untouched.

Full history in CHANGELOG.md.