Fix drag-n-drop plotting to respect distribution flag.

Refs #10743
Merge pull request #97 from mantidproject/bugfix/10743_drag_n_drop_plot_normalization

Fix drag-n-drop plotting to respect distribution flag.
Revert "Only have SofQW2 on Sqw tab"

This reverts commit f16cd217ad819a92d085dc18a6773ff4b60837e7.

Refs #10749
Sqw should be a choice between 2 and 3

Refs #10749
Merge branch 'feature/10749_add_sofqw3_back_to_sqw_tab' into develop