Fixes #41 (Toggle header does not work in 2 line file)
Show truncated cells

- Fix cell length width embedded newlines
- Move fixed defaults to header
- Use actual column width when displaying content
- Show truncated cells with a '>' character
Use insstr in order to be able to use the entire terminal width/height without scrolling.
Fixed/cleaned up the truncation_indicator code
Further truncation_indication fixup. Added padding/width command line options