Resolve "Clean code"

Closes #44

See merge request !42

Resolve "Upgrade flutter framework and dependencies"

Closes #42

See merge request !40

Resolve "Add GPLv3 license"

Closes #41

See merge request !39

Resolve "Replace images by personal or free images"

Closes #26

See merge request !38

Resolve "Add abstraction to allow other games"

Closes #33

See merge request !32

Resolve "Add fastlane metadata"

Closes #37

See merge request !37

Resolve "Improve select picture page"

Closes #39

See merge request !35

Resolve "Preload winning image"

Closes #38

See merge request !36

Resolve "Set fixed orientation"

Closes #40

See merge request !34

Resolve "Add minimal gameplay"

Closes #4

See merge request !33

Resolve "Add jabber notification on create tag"

Closes #36

See merge request !31

Resolve "Improve CI/CD, fix release, skip jobs"

Closes #35

See merge request !30

Resolve "Improve CI/CD, create tag on new release step"

Closes #32

See merge request !29

Resolve "Improve shuffling indicator"

Closes #11

See merge request !8

Resolve "Impove title bar, fix / add icons"

Closes #31

See merge request !28

Resolve "Improve title bar"

Closes #21

See merge request !19

Resolve "Set default tilesize to 4x4"

Closes #30

See merge request !27

Resolve "Remove non childproof images"

Closes #29

See merge request !26

Resolve "Improve convert pictures options"

Closes #28

See merge request !24

Resolve "Add pictures categories"

Closes #25

See merge request !25