Add compile(String) method

A convenience method to compile from String, analog to eval(String).

Author: Squareys

src/main/java/org/scijava/plugins/scripting/java/JavaEngine.java

@@ -160,6 +160,16 @@ public Object eval(Reader reader) throws ScriptException {
 		return null;
 	}
 
+	/**
+	 * Compiles and runs the specified {@code .java} class.
+	 * 
+	 * @param script the source code for a Java class
+	 * @return the compiled Java class as {@link Class}.
+	 */
+	public Class<?> compile(String script) throws ScriptException {
+		return compile(new StringReader(script));
+	}
+
 	/**
 	 * Compiles and runs the specified {@code .java} class.
 	 *