WIP - experimenting with dealing with multi-column inputs

This is an experimental branch, not for re-merging which holds code and tests for developing multicolumn detection.

For example:
https://bitbucket.org/scraperwikids/pdftables-test-data/src/dfcba82892655d29e0c9130ee4e18255d1fb2965/sample_data/COPAMONTHLYMay2013.pdf?at=master