Make right mouse do translation

[Tom Goddard]

I think we should change ChimeraX so that right-mouse does translation. Currently it does zooming and translation is done with middle-mouse as is done in Chimera 1. The problem is most computers do not have a 3-button mouse, nor any way to emulate a middle mouse button. What is common in today's computers (desktop and laptop) is that left and right mouse buttons or left and right trackpad clicks are available, as is scrolling (e.g. by one-finger drag on magic mouse, two finger drag on trackpads, right edge drag on older trackpads).

Since translation is quite important it should be easily accessible, hence the suggestion to make it right-mouse. Currently right mouse is zooming, but scrolling does zooming so that is already available.

This issue came up as I was trying to provide modifier keys on Windows to emulate middle and right mouse buttons. There is only one usable modifier Alt on Windows because the Windows key brings up the system menu.

[Tom Goddard]

Fixed.

Made right mouse button do translation by default. Middle mouse button continues to do translation. Zoom can be done by scrolling.