merge Histogram on the Evaluation screen when there's only 1 player

[rehtlaw]

Currently the histograms are split even if you are playing alone, this was because the Lifebar graph and Judgement histogram used to still be split in regular WF. As it is right now, the only difference between both sides is that whichever side shows an ITG panel at the moment, that histogram also changes to reflect the ITG lifebar/judgements.

This should be changed to the same behaviour as Simply Love, where it takes up the entire width of the two graphs for one long graph instead.

Thing to note:

• How would the judgements of the other game mode be handled? Do we just never show them? Since we want to allow for showing ITG judgements on the player's side's panes too, should we just follow whatever is shown on that side?