Make Linechart and Histrogram of DataPreprocessing more userfriendly

[pfleck]

The CheckedItemList of the features should be resizable.

Additionally, un- and re-checking a feature should not change the order in which features appear in the charts.

[pfleck]

r14268 Added SplitContainer in the PreprocessingChartView for splitting the list of features and the charts.

[pfleck]

r14270

• Fixed reordering issue by enabling/disabling series rather than removing the DataRow.
• Reduced flickering by suspending layouting during variable un/rechecking.

[mkommend]

r14371: Fixed minor type in comment of PreprocessingChartView (uncheckt -> unchecked).

[mkommend]

Reviewed & tested r14268, r14270. Everything described in this ticket (resizing and correct insert position) works perfectly.

However, I have tested with a problem data containing 50 features and ~5000 rows (feature selection benchmark problem) and noticed that selecting and deselecting multiple features in the linechart and histogram view is awfully slow. I don't know if that is connected to the changes in this ticket or if it has always been the case.

[pfleck]

Simultaneously selecting or deselecting multiple variables in the linechart and histrogram causes separate checked-changed-events. Each event triggers layouting, causing the linechart and histrogram to become slow.

This issue cannot be fix easily because the unterlying ListView does not offer multiple checked-changes in one event.

[mkommend]

r14796: Merged r14368, r14270, and r14371 to stable.