Resolve "Clean code"

Closes #9

See merge request !8

Resolve "Fix icon color"

Closes #6

See merge request !6

Resolve "Upgrade flutter framework and dependencies"

Closes #5

See merge request !5

Resolve "Add GPLv3 license"

Closes #4

See merge request !4

Resolve "Add a restart game button"

Closes #3

See merge request !3

Resolve "Add minimal gameplay"

Closes #2

See merge request !2

Resolve "Add minimal empty application"

Closes #1

See merge request !1