Plot help raises help on current tree item, which may not be relevant to the plot

[briantoby]

The help page that is raised from the help button should be the data tree item that created the plot not the currently selected tree item. If they are not the same, perhaps a warning to say that things are not going to work properly could be displayed.

[briantoby]

The supposition in this issue seems incorrect, in that the data tree item to be used for help is saved when the plot is created (in Page.helpKey) which is accessed in GSASIIplot.GSASIItoolbar.OnHelp so the "?" button on the taskbar raises the right help for the plot. However, if the data tree item as been changed so that the plot help information is now "stale," the user is now warned that they need to be in the right place in the data window.