Changes in 0.3-x releases of scatterplot3d:
=======
 0.3.0:  New design: box, pretty() for ticks, ...
 0.3.1:  par("las") bug patched, scale.y is changed (code and default)
 0.3.2:  all angles will work again (default: 40)
         tick mark labeling changed (using mtext)
         par("mar") is set in the first line, not very general!
 0.3.3:  new argument "mar", more details in the help files
 0.3.4:  new arguments x/y/z.ticklabs, thanks to Ben Bolker!
         bug fix: adj for tick.mark.labels corrected
 0.3-5:  new argument y.margin.add for manual fixing scaling problems
         (e.g. some y-tickmarks dissapear after rescaling the window)
 0.3-6:  cex.symbols introduced to solve magnification errors
 0.3-7:  added function plane3d, which will be returned,
         (e.g. for overlaying a regression plane)
 0.3-8:  bugfix: some magnification errors for y.ticklabs
 0.3-9:  bugfix: pch works vectorized again (error with y-sorting)
 0.3-10: added function box3d(), which will be returned,
         to draw the box surrounding the plot again after additions
         * added a function s3d.persp() - somehow joining s3d and persp() *
 0.3-11: * s3d.persp() deleted again, because of various reasons *
         Created this file to reduce the size of the R code.
 0.3-12: bug fix: tick.mark.labels of y axis were sometimes raised
         by a constant or vice versa
         format() is used to print tick.mark.labels pretty, and smarter
         calculation of desired (for y axis tick.mark.labels) plot margins
 0.3-13: typos in help file
         box3d() refreshes the right lines for an arbitrary angle now.
         calculation of space for tick.mark.labels fixed
         (bug was introduced with 0.3-12 ?)
         Extending s3d requires to set par(mar) to those settings
          s3d was generated with, which will be done for points3d(),
          plane3d(), and box3d() automatically.
          A "Note" has been added to the help file.
 0.3-14: Reference changed in help file.
         Suggestions by Martin Maechler (thank you!):
         - clean up a lot of code
         - Added note on unfixed bug to help file.
	 - Added Martin's great examples 6 a/b: "color cube"
 0.3-15: Allow for just 1 point (was 2 before) to be plotted
         Allow all points to be within a major plane
	 Argument lty.hide introduced (for plotting of in-visible edges)
	 plane3d() allows to plot the box-intersecting lines in a 
          different line style

known UNfixed bug:
 xlim, ylim, zlim don't work *exactly* for enlarged areas
