Fixed error in wrapping of arguments that are maps

wrappers/python/src/swig_doxygen/OpenMM.i

@@ -18,6 +18,7 @@ See https://simtk.org/home/pyopenmm for details"
 %include "std_string.i"
 %include "std_iostream.i"
 
+%include "std_map.i"
 %include "std_pair.i"
 %include "std_vector.i"
 namespace std {
@@ -28,6 +29,7 @@ namespace std {
   %template(vectorii) vector < vector<int> >;
   %template(vectorpairii) vector< pair<int,int> >;
   %template(vectorstring) vector<string>;
+  %template(mapstringstring) map<string,string>;
 };
 
 %include "windows.i"

wrappers/python/src/swig_doxygen/swig_lib/python/pythoncode.i

@@ -257,6 +257,17 @@ def stripUnits(args):
                 arg=arg.value_in_unit_system(unit.md_unit_system)                
             # JDC: End workaround.
             #arg=arg.value_in_unit_system(unit.md_unit_system)
+        elif isinstance(arg, dict):
+            newArg = {}
+            for key in arg:
+                newKey = key
+                newValue = arg[key]
+                if not _is_string(newKey):
+                    newKey = stripUnits(newKey)
+                if not _is_string(newValue):
+                    newValue = stripUnits(newValue)
+                newArg[newKey] = newValue
+            arg = newArg
         elif not _is_string(arg):
             try:
                 iter(arg)