Add session kwarg to ModelicaSystem constructor

If the session kwarg is specified, the ModelicaSystem will use that
session instead of creating a new one. This is useful for creating a
ModelicaSystem for a model that is already loaded in an already existing
session.

Author: AxelMatstoms

OMPython/__init__.py

@@ -821,7 +821,7 @@ class ModelicaSystem(object):
     def __init__(self, fileName=None, modelName=None, lmodel=None,
                  useCorba=False, commandLineOptions=None,
                  variableFilter=None, customBuildDirectory=None, verbose=True, raiseerrors=False,
-                 omhome: str = None):  # 1
+                 omhome: str = None, session: OMCSessionBase = None):  # 1
         """
         "constructor"
         It initializes to load file and build a model, generating object, exe, xml, mat, and json files. etc. It can be called :
@@ -857,10 +857,13 @@ def __init__(self, fileName=None, modelName=None, lmodel=None,
 
         self._verbose = verbose
 
-        if useCorba:
-            self.getconn = OMCSession(omhome=omhome)
+        if session is not None:
+            self.getconn = session
         else:
-            self.getconn = OMCSessionZMQ(omhome=omhome)
+            if useCorba:
+                self.getconn = OMCSession(omhome=omhome)
+            else:
+                self.getconn = OMCSessionZMQ(omhome=omhome)
 
         ## needed for properly deleting the OMCSessionZMQ
         self._omc_log_file = self.getconn._omc_log_file