* Add ability to zoom in on small images

* Update image viewer to allow pinch or click to zoom

Images are now always centered in the window. They initially start at
their native size, unless they would be larger than the window, in which
case they are contained within the window. Clicking increases the
zoom, and alt+click decreases it. Pinch to zoom and ctrl+scroll are also
supported.

* Update resourceViewer to improve image viewing experience

ResourceViewer now holds a cache of image scales so they stay the same
while flipping between editor tabs. Right clicking now returns the image
to its original scale. Pixelation only triggers for images 64x64 or
smaller, and only after the first zoom. Editor risizing is handled
thorugh the layout call to the binary editor, passed down to the
resource viewer.