Geometric image attributes are not correctly linked for image stacks

[Daniel Scharrer]

Steps to reproduce:
- Add multiple images and control points.
- Link images into stacks. (Images tab -> Change stack...)
- Unlink some geometric properties (hfov (v), distortion (a,b,c), center shift(d,e), image shearing(g,t): Uncheck "Link" in "Camera and Lens" -> "Geometric"
- Optimize / align

Expected results:
- All images in the same stack have the same geometric properties.

Actual results:
- Each image has different properties

Additional details:
The affected properties' values are saved for each image in the .pto file, unlike yaw (y), pitch (p), roll (r), which are only saved for the first image in the stack and then liked from the other image using the y=image_index notation.
If I manually change the values to links using the v=image_index notation, Hugin loads the correct values for the images, but
a) Thinks the values are linked for the whole project, even though they were only linked for each stack.
b) When unliking the images again, optimization will not produces different values for each image in the stacks, as described above.
c) Saving the project again writes the values for each image and not the links that were there.

Hugin version: 2011.0.0.0f9fdaf56720

[tmodes (tmodes)]

Hugin is using the concept of lens and stacks. So it is not possible to separately link the geometric parameters in a stack alone (this is allowed in panotools, but not used in Hugin).
So for now Hugin prints a warning, if the stacks are incorrectly linked (changeset 624abeb108a1c8ba1bd566b74b173b4d7202c23c).