0.83: Additional information in Copy/Move overwrite dialog

[pangwolin]

When the same filename is found, the overwrite dialog prompt is missing several important things, namely:
* filesize of each file
* filename of each file
* estimated quality of each file

Not sure if this is a Linux only thing or not.


Also, a "quick compare" button as show above would be really handy. (it essentially swaps both viewports to see differences between two files).

If XnViewMP was open source, I would have tried to add this myself...

[XnTriq]

I'd also like to request the features and layout of XnView Classic's overwrite dialog be added to that of MP.

Related requests:

• XnView Classic: Revamped replace/overwrite dialog (implemented)
• XnView MP: Add in-place compare to export dialog!