Implement save/re-open crosswords

Context

Implements #39 (closed).

What has changed?

Main Changes

puzzle-codec-xd

• A codec for the xd format, a text crossword puzzle format

spi-puzzle-repository

• New spi-puzzle-repository defining a CRUD puzzle storage

puzzle-repository-memory-plugin

• An implementation of spi-puzzle-repository that works purely in memory. First implementation made, only used for tests.

puzzle-repository-filesystem-plugin

• An implementation of spi-puzzle-repository that works with files on disk.

spi-presenter

• Added PuzzlePresenter gather puzzle repository-related presentation method definitions

common

• Added puzzle types

core

• Added puzzle service that allows to manage saved puzzles. Mainly boilerplate to interact with the puzzle repository and the presenter
• Added the possibility to save puzzle on a solve request.

tests

• Added tests for the puzzle service

cli

• Implemented control and presentation.

gui

• Implemented control and presentation. Highlights:
  • New welcome screen allowing to visualize puzzle in repository, select a puzzle to edit or to delete from repository
  • New left pane to edit puzzle details
  • New save buttons

Side Effects

common

• Breaking changes, moved types around, reworked types

gui-*

• Lots of changes going from icon theme update to cutting the dependency between gui-view-model and common

Reviewers

The MR is huge. Development was actually made in smaller chunks: See #39 (closed) for list of individual MRs.

Let's see how things fit together now. Hopefully, there won't be big surprises at this point.