Full table area not being detected

Link to PDF: https://stackoverflow.com/questions/53203779/headers-are-not-getting-extracted-from-pdf-while-extracting-the-table-data-from

Steps to reproduce: `camelot -p 3 lattice -plot contour 007.pdf`


Start by reproducing the issue with `camelot -p 3 lattice -plot contour 007.pdf` and review the linked Stack Overflow question and contour image. Trace the table-area detection used by the lattice command; done means the full table area in the supplied PDF is detected rather than only the partial region shown.

Written by the indexing model from the issue text.