pdPageExtractText should support multi-column documents

[sambitdash]

This implementation may be needed to be reviewed along with #2. Although, there may not be an exact overlap in some cases the implementation logic can be similar.

[Nosferican]

Is there any way to currently do this?

[sambitdash]

Not really. You can manually estimate every textrun and see if they form a column. The specification does not provide any structural hints for the same.

[vargonis]

On a related note, since by the nature of the format the output of pdPageExtractText is not fully determined, it would be useful to:

1. Have access to character level information (font, bounding box and so on).
2. Document what the word inference and ordering heuristics are.

[sambitdash]

@vargonis you can use pdPageEvalContent and get the content tree. The content tree has all the bounding box information at a text run level.