Use a move's full description in the move sheet

[ben]

Fixes #259. Dataforged provides the text we'd want for a full description of a move without the bother of reconstructing it from component bits. We just had to store and display it.

• Store the full descriptive text for moves
• Show it in the move sheet (Starforged only, that's the only data we have)
• Add an editor to the move item sheet
• Update CHANGELOG.md