Add language support plugin for Groovy.

The functionality seems to be limited for now:
- the def keyword is required for tokens to be recognized
- built-in keywords such as println are not suggested

src/main/java/org/scijava/ui/swing/script/languagesupport/GroovyLanguageSupportPlugin.java

@@ -0,0 +1,59 @@
+/*
+ * #%L
+ * Script Editor and Interpreter for SciJava script languages.
+ * %%
+ * Copyright (C) 2009 - 2020 Board of Regents of the University of
+ * Wisconsin-Madison, Max Planck Institute of Molecular Cell Biology and
+ * Genetics, and others.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+
+package org.scijava.ui.swing.script.languagesupport;
+
+import org.fife.rsta.ac.groovy.GroovyLanguageSupport;
+import org.scijava.plugin.Plugin;
+import org.scijava.ui.swing.script.LanguageSupportPlugin;
+import org.scijava.ui.swing.script.LanguageSupportService;
+
+/**
+ * {@link LanguageSupportPlugin} for the groovy language.
+ *
+ * @author Jan Eglinger
+ * @see GroovyLanguageSupport
+ * @see LanguageSupportService
+ */
+@Plugin(type = LanguageSupportPlugin.class)
+public class GroovyLanguageSupportPlugin extends GroovyLanguageSupport
+	implements LanguageSupportPlugin
+{
+
+	public GroovyLanguageSupportPlugin() {
+		super();
+	}
+
+	@Override
+	public String getLanguageName() {
+		return "groovy";
+	}
+}