Subroutine densplot

As an example of what can be done to output interesting information from the code, we include a routine named DENSPLOT in densplot.f. It calculates the SPH density for a 3-d grid, whose size is set by parameters within the file. The results are saved by converting the data to an integer between 0 and 255, and converting this to a character, which is stored in binary format, taking up one byte per element. Results can be scaled against either the maximum density present on the grid, or a user-defined value. Output files are saved in the format ``densxxxx.dat'', where ``xxxx'' is a 4-digit integer equal to the parameter NIT, the iteration count.