Removed redundant convertStrings=False when starting Java VM.

This has been the default since JPype 0.7.4 (see its changelog)
and we probably never needed it anyway as we always do an explicit
string conversion when we receive a Java string.

mph/client.py

@@ -164,13 +164,12 @@ def __init__(self, cores=None, version=None, port=None, host='localhost'):
         # Start the Java virtual machine.
         log.debug(f'JPype version is {jpype.__version__}.')
         log.info('Starting Java virtual machine.')
-        java_args = [str(backend['jvm'])]
+        root = backend['root']
+        args = [str(backend['jvm'])]
         if option('classkit'):
-            java_args += ['-Dcs.ckl']
-        log.debug(f'JVM arguments: {java_args}')
-        jpype.startJVM(*java_args,
-                       classpath=str(backend['root']/'plugins'/'*'),
-                       convertStrings=False)
+            args += ['-Dcs.ckl']
+        log.debug(f'JVM arguments: {args}')
+        jpype.startJVM(*args, classpath=str(root/'plugins'/'*'))
         log.info('Java virtual machine has started.')
 
         # Import Comsol client object, a static class, i.e. singleton.