Version 0.6.2

This is now on CRAN.

Version 0.6.0

Changes from version 0.5.1 are as follows. See NEWS.md for more about versions.

• Add shipMassFromLength().
• Add shipLength().
• Update app() to use collapsible GUI elements and to have pull-down menus
  for ship type and whale species, the selection of which alters the sliders
  that set for ship and whale properties.