Allow Quick Copy to be site-specific

[dstillman]

Allow users to customize the Quick Copy format on a per-site basis, either to affect the keyboard shortcut or a drag a drop feature into text areas

[dstillman]

(In [1389]) Closes #601, Allow Quick Copy to be site-specific
Closes #560, Method for inserting bibliography/export format into text box on current page

Dragging items to external text apps is also possible now (the one oddity being that the format has to be set at the beginning of the drag session, so if the window's current page matches a site-specific setting, the dragged references will use that format even the if the text is dropped into an external app or another window)

[dstillman]

(In [1390]) Addresses #601, Allow Quick Copy to be site-specific
Addresses #560, Method for inserting bibliography/export format into text box on current page

Missed file from r1389