WRITE expression

   Synopsis:
      Writes a system message to the 'main' window

   Notes:
      The message is preceded by the text "AXBASIC: " (in contrast, a PRINT
         statement writes a message to the 'main' window without any such
         identifier).
      The message is also written to Axmud's logfiles (if logging is enabled).
      See also the help for DEBUG, ERROR, PRINT and WARNING.

   Examples:
      WRITE "Hello world!"
