Note that universe files are now stored in ~/.planets, so you might want to
drop the uni.9 example universe there.

Normal keybindings

   H                Display help dialog
   a                Add Planet
   =                Zoom In
   -                Zoom Out
   B                Toggle true bounce
   b                Toggle bounce
   c, space                 Center
   k                Display option dialog
   o                Change all colors
   q, Escape        Quit
   e                Reset to empty universe
   s                Save Universe
   l                Load Universe
   u                Undo (undoes last planet insertion)
   g                Go Back (goes back to last planet insertion)
   p                Toggle Pause
   t                Toggle Trace
   d                Double Trace Length
   h                Halve Trace Length
   j                Place random orbital planet
   r                Place random planet
   x                Initiate C-O-M tracking
   Up               Pan Up
   Down             Pan Down
   Left             Pan Left
   Right            Pan Right

Also:

  * Drag a box around a set of planets to follow the center of mass of those
    planets.
  * Click on a planet to delete it


Kidmode bindings:

numbers : toggle tracing
q,w,e,a,s,d,z,x,c: change colors
space: move to center of mass
escape: erase all planets
all other buttons: add random planet