Write failed solution when restart_failed_analysis is False (#343)

* Write failed solution when restart_failed_analysis is False

* Option to specify number of leading zeros in solution filename number (#345)

* New option for digits in solution filename numbering

* Fixed incorrect option name

* Specified solution digits for failed mesh too

adflow/mphys/mphys_adflow.py

@@ -559,6 +559,11 @@ def solve_nonlinear(self, inputs, outputs):
                         print("###############################################################")
                         print("# Solve Failed, not attempting a clean restart")
                         print("###############################################################")
+
+                    # write the solution so that we can diagnose
+                    solver.writeSolution(baseName="analysis_fail", number=self.solution_counter)
+                    self.solution_counter += 1
+
                     raise AnalysisError("ADFLOW Solver Fatal Fail")
 
                 else: