updated detailed system plotter script to output png as well as eps. eps is for the methods paper, png is for the getting_started doc

Author: reinhold-willcox

docs/getting_started.md

@@ -184,7 +184,7 @@ We examine `BSE_Detailed_Output_0.h5` to look at the evolution of the two stars.
     python3 single_sys_plotter.py
 
 This should produce the following plot:  
-![demo_plot](../examples/methods_paper_plots/detailed_evolution/gw151226evol.eps)
+![demo_plot](../examples/methods_paper_plots/detailed_evolution/gw151226evol.png)
 
 
 COMPAS provides many tools for analysing and post-processing the data. Please view the post-processing documentation in `COMPAS/postProcessing`. 

examples/methods_paper_plots/detailed_evolution/detailed_evol_plotter.py

@@ -85,6 +85,7 @@ def main():
     fig.subplots_adjust(left=0.05)  #adjusting boundaries of the plotter
     fig.subplots_adjust(wspace=.3)
     plt.savefig('gw151226evol.eps', format='eps') 
+    plt.savefig('gw151226evol.png', format='png') 
     plt.show()