Three .cpp files were incorrectly listed in SOURCE_GROUP_HEADER_FILES instead of their
corresponding .h files, causing each to be compiled twice in unity builds and producing
duplicate symbol linker errors (LNK2005) and unresolved externals (LNK2019).
* Add drag'n'drop support for ensemble summary vectors and ensembles into histogram plots
* Make sure histogram plot is shown and all update signals are connected when loading a project.
* Support ensemble parameter drag'n'drop from data sources into histogram plots.
* Show ensemble parameters in data sources tree.
* Add copy/paste of histogram curves
* Re-use all existing parameters in a plot when dragging a new ensemble into it