Compilation instructions under unix/linux

- the Vibrant library is needed

- motif or lesstif are needed

- optionally, the PDFLib Lite library is used: compile with -DNO_PDF not to use it.

- modify the makefile to reflect locations of Vibrant, Motif, PDFLib Lite include files
and libraries.

- optionally, compile by defining HELPFILENAME to the full pathname (with enclosing "") of 
the help file. If not done, file njplot.help is searched in all directories of the PATH.
