Add a reactor right click menu and put there a button to swap waldo colors

[12345ieee]

The game has no right click menu when not hovering over a symbol, so we can put there our own to do global actions on symbol groups, like:

• [x] color swapping
• [x] mirror vertically
• [x] reset reactor
• [ ] save to toolbox for researches (how to load it back remains to be seen)

That menu would also be a good place to add other level-related commands like the tourney logic of #24 .

[csaboka]

All but one of the subtasks have been implemented in v1013 of the main game. Created #2 in Community Edition to track the remaining subtask. I'm closing this issue now.