Prepend jre\bin folder to Windows search path before loading JVM.

This should fix issue #49.

mph/client.py

@@ -161,6 +161,12 @@ def __init__(self, cores=None, version=None, port=None, host='localhost'):
             log.debug('Turning off Python fault handlers.')
             faulthandler.disable()
 
+        # On Windows, prepend the Java folder to the library search path.
+        # See issue #49.
+        if platform.system() == 'Windows':
+            path = os.environ['PATH']
+            os.environ['PATH'] = str(backend['java']) + os.pathsep + path
+
         # Start the Java virtual machine.
         log.debug(f'JPype version is {jpype.__version__}.')
         log.info('Starting Java virtual machine.')
@@ -211,7 +217,7 @@ def __init__(self, cores=None, version=None, port=None, host='localhost'):
                 try:
                     java.setPreference(name, value)
                 except Exception:
-                    log.info(f'Preference {name} does not exist.')
+                    log.info(f'Preference "{name}" does not exist.')
 
             # Log that we're done so the start-up time may be inspected.
             log.info('Stand-alone client initialized.')

mph/discovery.py

@@ -188,6 +188,7 @@ def search_Windows():
             'patch':  patch,
             'build':  build,
             'root':   root,
+            'java':   java,
             'jvm':    jvm,
             'server': [server],
         })
@@ -277,6 +278,7 @@ def search_Linux():
             'build':  build,
             'root':   root,
             'jvm':    jvm,
+            'java':   java,
             'server': [comsol, 'mphserver'],
         })
 
@@ -367,6 +369,7 @@ def search_macOS():
             'build':  build,
             'root':   root,
             'jvm':    jvm,
+            'java':   java,
             'server': [comsol, 'mphserver'],
         })