Fixed missing argument in current function calls with snapshots. Occurred due to updating function arguments for calculating currents.

gprMax/_version.py

@@ -1,3 +1,3 @@
 # This is where the version number is set and read by setup.py and conf.py (for the docs)
 
-__version__ = '3.0.15'
+__version__ = '3.0.16'