Drop unused spice-gtk source files
Drop unused virt-viewer-file support code
Drop leftover LICENSE file from Opaque

Drop LICENSE file claiming JNI glue is under GPLv3, since all GPLv3 code
has been removed.
Drop more unused spice-gtk source files
Drop unused fields in NDK glue structs
Drop some unused variables
Limit visibility of member variables where possible
Drop some unused utility methods
Drop unused input mode validation in scaling implementations
Drop RemoteCanvasActivity.getConnection()
Drop unused followMouse option

and remains of followPan menu entry.
Drop followPan

It was only enabled for simulated touchpad mode, where it doesn't
actually do anything.  Also, if enabled in absolute-mouse mode by
modifying the code, it turns out not to provide a very good user
experience.
Automatically select input mode based on VM support for absolute mouse
Drop manual selection of input mode
Rename input handler classes
Minor SpiceCommunicator cleanups
Fix some warnings