0.1.0 --------------------------------------------------------------------
  initial version. minimal set of features

0.1.1 --------------------------------------------------------------------
  fixes to drawing, minor bugs

0.2.0 --------------------------------------------------------------------
  more features: added keyboard input
                 new parameter saving
                 saving data is now optional
                 file load/save support

0.2.1 --------------------------------------------------------------------
  fixed makefile. added pd_darwin target

0.2.2 --------------------------------------------------------------------
  added send/receive symbols support

0.2.3 --------------------------------------------------------------------
  numbers are now aligned to right
  notification messages are sent from user interaction
  mouse behavior improved. now dragging faster changes more.
  added nice makefile for target:
    Linux
    MacOS (thanks Steffen)
    Win32 (thanks tof)