PATCH: lensfun support for align_image_stack

[Vladimir Nadvornik]

Hi,

the attached patch adds --lensfun option to align_image_stack command.

I found it necessary for processing uncorrected raw files from Canon S95, where the distortion
is really significant.

[tmodes (tmodes)]

Thanks for the patch. But it needs some more work:
1.) The lensfun database needs to correctly initialized (I assume you are on Linux, where lensfun is compiled with a fixed path, where this is not needed. But on other OS lensfun needs to correctly initialized before reading.)
2.) pto_gen is using the switch --distortion. For consistency I propose to use the same here instead of --lensfun.

[Vladimir Nadvornik (nadvornik-suse)]

OK, I will look into it.

[Vladimir Nadvornik (nadvornik-suse)]

Here is new patch.

Lensfun init is untested, I can compile it only on linux. It is just copied from pto_gen.

There was also a bug in parsing --corr value, the patch fixes it.

[tmodes (tmodes)]

Thanks. Committed to repository.
Some additional includes were necessary to compile it again.