Add Preprocessing

[willnilges]

Add Preprocessing

[WillNilges]

I wonder if I can effectively straighten the image as well (or somehow ask the user to do it manually)

[WillNilges]

I wonder if we could make OpenCV auto-crop by singling out white rectangles in the image and removing the rest of the pixels. Maybe we can also make it auto-straighten by trying to straighten out the edges like we did with the pool table.

[WillNilges]

I'm going to be using some userdata bullshittery to get data from OpenCV to my Lua plugin. From there, I'll go stroke-by-stroke, pushing things onto the Lua stack and passing them to Xournalpp. A possible optimization to make down the line would be to skip the Lua stack altogether and just shunt contours directly to Xournalpp somehow.

[WillNilges]

TODO: build and install OpenCV in the Dockerfile :3

[WillNilges]

Seems like inkpath doesn't like plusses or T's. Hmm.