#31 - Added some more features of the UI. Right-Click opens a Context Menu

[macskay]

• 31 - Right clicking now opens a context menu, which is different for items in space, items in bags and free space of the map.

• The context menu closes, when the bag is opened, as well as when left clicking in free space
• At the moment the only functionality of the Context-Menu is printing the respective label.

This pull request is to make sure everything works with the new item-system

TODO: Implementation of the actual features when clicking a button of the context menu.

[landscape-bot]

Repository health decreased by 2% when pulling 9f2a6b4 on enhancement/31-right-click-context-menu into 964e2f1 on master.

• 3 new problems were found (including 2 errors and 0 code smells).
• No problems were fixed.

[landscape-bot]

Code quality remained the same when pulling 72addd0 on mkli90:enhancement/31-right-click-context-menu into 964e2f1 on mkli90:master.