removed unnecessary import

src/main/java/plugins/stef/roi/bloc/RoiBlocks.java

 package plugins.stef.roi.bloc;
 
 import icy.main.Icy;
-import icy.plugin.PluginDescriptor;
 import icy.plugin.PluginLauncher;
 import icy.plugin.PluginLoader;
 import icy.plugin.abstract_.Plugin;