Implementation to allow Jump To fields to be more dynamic

This is for issue 1636, Jump To field.

This field now contains the relevant categories in the drop down menu depending on the currently selected column (i.e. User Name, First Name, or Last Name)

So if table is sorted by user name, the Jump To field will contain categories with user names in them. Ditto for First names and Last Names
Line is too long. [86/80]