future feature:
--lines -40 (consider `-' as `less than') (not easy, would be default)
find N so that (1) (N < 40) and (2) TOTAL%N is either 0 or maximal and (3) N is minimal)
(1) because of paper size and readability in general. N is lines-per-tabular
(2) do not have a near-to-empty tabular. TOTAl%N is lines-for-the-latest-tabular
(3) do not make useless small tabulars. TOTAL/N is the number of tabulars
- is this a correct definition ?

possible feature:
--reduce auto (not easy, would be default)
compute --reduce due to linelength and \textwidth.

possible feature:
--lines auto (would be default)
compute --lines due to fontsize and \textheight.
