Corrected some logic in AlphaBlend4bbp which was not considering stride widths and logical column indexes correctly in its traversal. This would lead to non aligned images being rendered incorrectly.
Improved GifDecoder<T>.DataBuffer.FillBuffer by adding a parameter indicating if the delegates returned fixed values, allowing the tight loop setting values on aligned bytes to cache the value in advance for improved speed. This greatly reduces the time spent clearing buffer regions after drawing frames.
Added a very specific optimization in WinFormSpriteInterface to check incoming GIF buffers to decode to see if they can be losslessly downscaled by a factor of 2, this is because most images in Desktop Ponies are inflated by this scale factor, thus consuming 4x the required memory. The images cannot be rescaled since that would be a breaking change for ports, so instead we do a runtime check. This optimization is extremely specific and should be moved into the Desktop Ponies assembly if a nice way can be found of doing so.
Extracted 32-bit FNV-1a hashing function into a reusable class.
Improved speed of TryDownscale methods by extracting repeated calculations into variables.
Added some dialogs warning of closing tabs with unsaved changes to the new editor.

Dispose of the preview a bit earlier in the close process so the preview window isn't seen hanging around for a few moments after the editor window closes.
Corrected minor errors in handling of size and location when drawing images using the AnimatedImageViewer or EffectImageViewer to account for border size.

Improved PonySelectionControl to fix minor error in handling of image size and apply a consistent margin.