ToDo list for debtree
---------------------
* add "usage" function and --version and --help options
* this code really needs a testsuite as regressions are many and subtle;
  comparing the .dot output with expected would be simpler if a fixed
  status database was used
* complete conversion to perl by using libapt-pkg-perl instead of calls
  to dctrl-tools
* automatic limiting
* automatically split graphs over multiple subgraphs (which dot will place
  on separate pages)
* identify transitional packages