Improve layout detection

[alexanderadam]

First of all: pd3f is working great!
It's a wonderful tool. Thank you so much for creating it.

There's this small issue though, that text blocks / columns aren't recognized as such. So articles written in columns and similar things are currently not recognized within their blocks.
Thus highlighting or searching things that span over a line is broken in these cases.

I'm not sure why this is the case, since I though that tesseract has actually a proper layout analysis integrated ("Page Segmentation Mode" and its default should be "Fully automatic page segmentation, but no OSD").

[jfilter]

Hey Alexander,

I'm unfortunately very busy until March. I'm also not satisfied of the column detection and will improve it.