nth-user

Results 3 issues of nth-user

Currently the frame will be redrawn every time the user tries to zoom above 500%. This PR prevents that behaviour by checking if the `Zoom` value actually changed.

Allows dragging the page when pressing and holding the middle mouse button.

## Reduce rendering overhead Removed dependency on System.Drawing.Image and render directly to a WPF ImageSource. This also fixes the memory leak and all calls to `GC.Collect()` have been removed. ##...