Resolve "Restore custom font"

Closes #92

See merge request !87

Resolve "Normalize Activity application architecture"

Closes #90

See merge request !86

Resolve "Use ApplicationSettings widgets from flutter_custom_toolbox"

Closes #89

See merge request !85

Resolve "Use flutter_custom_toolbox for common features"

Closes #88

See merge request !84

Resolve "Re-order ABI builds"

Closes #87

See merge request !83

Resolve "Improve build process"

Closes #86

See merge request !82

Resolve "Clean / improve / update code"

Closes #85

See merge request !81

Resolve "Normalize game architecture"

Closes #83

See merge request !79

Resolve "Add "about" page"

Closes #81

See merge request !77

Resolve "Add "settings" page"

Closes #79

See merge request !74

Resolve "Restore "save / resume game" feature"

Closes #80

See merge request !76

Resolve "Add "settings / game / board / cell" models"

Closes #74

See merge request !73

Resolve "Add a delay after use help button to reactivate"

Closes #43

See merge request !45

Resolve "Improve game architecture"

Closes #73

See merge request !68

Merge branch '78-improve-ci-cd-remove-update-step-disable-build-debug-in-master-branch' into 'master'

Resolve "Improve CI/CD, remove "update" step, disable "build-debug" in master branch"

Closes #78

See merge request !72

Resolve "Avoid print calls in production code"

Closes #77

See merge request !71

Resolve "Remove deprecation in flutter gradle plugin"

Closes #76

See merge request !70

Resolve "Use flutter linter and apply lints"

Closes #75

See merge request !69

Resolve "Upgrade framework, build tools and dependencies"

Closes #72

See merge request !67

Resolve "Remove iOS variant"

Closes #70

See merge request !66