Filter out Jython classes when reloading the plugins

This prevents the Console from being flooded with messages such as:
Class 'plugins.tlecomte.jythonForIcy.Lib.re$py' cannot be loaded :
Required class 'plugins.tlecomte.jythonForIcy.Lib.re$py (wrong name:
re$py)' not found.
Merge pull request #527 from tlecomte/ignore-python-classes-in-loader

Filter out Jython classes when reloading the plugins