Short term:
-----------
- Composite:
   When using bars in both, an option is necessary to define whether
   to put the bars above each other or to put aside.
   Add an option to start x-ticks at the left (i.e. 0 point) side and
   end at the right side
-  Adapt true/false also to proper Perl true/false definition
   (i.e. false = undef || 0 || "0",
         true  = def || 1 || "1")
-  Reorganize the relationship between
   autoscale, 
   y_ticks, min_y_ticks, max_y_ticks, xy-plot, integer_ticks_only, skip_int_ticks,
   min_val, max_val
   and document it.
   (At the moment the autoscale is used as the default)
-  Include Skyplot (Direction->polar) into the distribution   

Long term:
----------
- 3-D charts
- include TrueType fonts as soon as GD supports it
- include logarithmic x- and y-axis
- Let plot arbitrary xy-functions in a defined area, like
  y=sin(1/x)+2*x
