Things that should be done:
- Add support for whitespace around images
- Add support for defining paper size per page instead of per pdf ( trivial )
- Add more paper definitions ( only have A4 / letter currently )

Things that could be done:
- Cleaner handling of data ( ie field ) headers
- Support calculating a header's row that contains an unscaled image when determining our $y_needed
    This situation should be quite rare, and it would need a different approach
    We'd have to do a dummy render_row pass on each header, or else break out our calculation into another function?
