Add camera lens/sensor shift support with horizontal/vertical shift
adjusters.
Add shifting and rotation of corrected image. This allows
post-correction adjustments to be made more easily given the fixed image
canvas size.
Add scaling of final result. This also helps reduce frustrations with
the fixed image canvas size.
Replace field of view with focal length and crop factor. Use of focal
length and crop factor is more common than diagonal angular field of
view. The new adjusters should be more intuitive for most photographers.
The implementation of perspective correction uses a focal length
relative to the image dimensions. The existing code calculates that
focal length with trigonometry. The new code does it by multiplying
by a ratio.
Replace vertical bias with horizontal and vertical perspective
distortion recovery. Vertical bias is not intuitive as it causes
vertical lines to converge off-center if horizontal correction is
applied. The new adjusters perform perspective distortion on the
projection of the corrected image, allowing vertical/horizontal lines to
converge towards the center lines of the image.
Refactor perspective transformation math to use dynamically computed
homogeneous coordinate matrices instead of pre-calculated formulas. This
should add some overhead, but results in more maintainable code and
possible improved performance due to the reduced number of arithmetic
and assignments needed for each pixel.
Integrate new adjusters in the GUI. This includes fine granularity for
batch processing add/set modes and history.
