[WIP] Support for Pentax PixelShift

[maruncz]

This PR adds support for multiframe raws into rawprepare, temperature and demosaic modules.
This enables demosaic module to merge them together.

This PR requres to merge this darktable-org/rawspeed#350

There is only basic pixelshift algorithm implemented, ultimate goal is closer to what rawtherapee is doing, but i think that will be in next PRs.

Because i have no prior experience with OpenCL or OpenMP, i only implemented basic CPU paths.

There are some leftover debug printfs, i'll remove them at the end.

[maruncz]

I would like to add more description.

First I had to modify rawspeed to support multiple frames, this unfortunately breaks API.

Then i had to modify dt_iop_buffer_dsc_t to account for multiple frames, all frames are merged togrther in one buffer.
This also meant i had to modify all places that allocate those buffers.

Pixelshift algorithm is implemented in demosaic. This meant that i had to modify rawprepare and temperature modules, because those are before demosaic in pixelpipe.
If there is another module that comes before demosaic, please let me now.

Before I attempt to do speed optimizations, please let me now, if this PR has any chance of merging.

[github-actions]

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[github-actions]

This pull request has been marked as stale due to inactivity for the last 60 days. It will be automatically closed in 300 days if no update occurs. Please verify it has no conflicts with the master branch and rebase if needed. Mention it now if you need help or give permission to other people to finish your work.

[github-actions]

This pull reguest was closed because it has been inactive for 300 days since being marked as stale.