Add Frege language

What is Frege?
-------------
Frege is a non-strict, pure functional programming language in the spirit of Haskell for the JVM.
It enjoys a strong static type system with type inference.
Higher rank types are supported, though type annotations are required for that.

Frege programs are compiled to Java and run in a JVM.
Existing Java Classes and Methods can be used seamlessly from Frege.

The Frege programming language is named after and in honor of Gottlob Frege.

Project State:
-------------
The compiler, an Eclipse plugin and a provisional version of the documentation can be downloaded
from here https://github.com/Frege/frege/releases.

The REPL can be downloaded from here
https://github.com/Frege/frege-repl/releases.

An online REPL is running here
http://try.frege-lang.org/.

Examples:
--------
1) Command Line Clock: https://github.com/Frege/frege/blob/master/examples/CommandLineClock.fr
2) Brainfuck: https://github.com/Frege/frege/blob/master/examples/Brainfuck.fr
3) Concurrency: https://github.com/Frege/frege/blob/master/examples/Concurrent.fr
4) Sudoku: https://github.com/Frege/frege/blob/master/examples/Sudoku.fr
5) Java Swing examples: https://github.com/Frege/frege/blob/master/examples/SwingExamples.fr

samples/Frege/SwingExamples.fr

@@ -0,0 +1,79 @@
+package examples.SwingExamples where
+
+import Java.Awt  (ActionListener)
+import Java.Swing
+
+
+main _ = do
+    rs <- mapM Runnable.new [helloWorldGUI, buttonDemoGUI, celsiusConverterGUI]
+    mapM_ invokeLater rs
+    println "Hit enter to end ...."
+    s <- getLine
+    return ()
+
+celsiusConverterGUI = do
+    tempTextField   <- JTextField.new()
+    celsiusLabel    <- JLabel.new ()
+    convertButton   <- JButton.new ()
+    fahrenheitLabel <- JLabel.new () 
+    frame           <- JFrame.new ()
+    frame.setDefaultCloseOperation JFrame.dispose_on_close
+    frame.setTitle "Celsius Converter"
+    celsiusLabel.setText  "Celsius"
+    convertButton.setText "Convert"
+    let convertButtonActionPerformed _ = do
+            celsius <- tempTextField.getText
+            case celsius.double of
+                Left _  -> fahrenheitLabel.setText ("not a valid number: " ++ celsius)
+                Right c -> fahrenheitLabel.setText (show (c*1.8 + 32.0).long ++ " Fahrenheit") 
+            return ()
+    ActionListener.new convertButtonActionPerformed >>= convertButton.addActionListener
+    fahrenheitLabel.setText "Fahrenheit"
+    contentPane <- frame.getContentPane
+    layout      <- GroupLayout.new contentPane
+    contentPane.setLayout layout
+    -- TODO continue
+    -- http://docs.oracle.com/javase/tutorial/displayCode.html?code=http://docs.oracle.com/javase/tutorial/uiswing/examples/learn/CelsiusConverterProject/src/learn/CelsiusConverterGUI.java
+    frame.pack
+    frame.setVisible true
+
+helloWorldGUI = do
+    frame <- JFrame.new "Hello World Frege"
+    frame.setDefaultCloseOperation(JFrame.dispose_on_close)
+    label <- JLabel.new "Hello World!"
+    cp <- frame.getContentPane
+    cp.add label
+    frame.pack
+    frame.setVisible true
+
+buttonDemoGUI = do
+    frame <- JFrame.new "Button Demo"
+    frame.setDefaultCloseOperation(JFrame.dispose_on_close)
+    newContentPane <- JPanel.new ()
+    b1::JButton <- JButton.new "Disable middle button"
+    b1.setVerticalTextPosition   SwingConstants.center
+    b1.setHorizontalTextPosition SwingConstants.leading
+    b2::JButton <- JButton.new "Middle button"
+    b2.setVerticalTextPosition   SwingConstants.center
+    b2.setHorizontalTextPosition SwingConstants.leading
+    b3::JButton <- JButton.new "Enable middle button"
+    b3.setVerticalTextPosition   SwingConstants.center
+    b3.setHorizontalTextPosition SwingConstants.leading
+    b3.setEnabled false
+    let action1 _ = do
+            b2.setEnabled false
+            b1.setEnabled false
+            b3.setEnabled true
+        action3 _ = do
+            b2.setEnabled true
+            b1.setEnabled true
+            b3.setEnabled false
+    ActionListener.new action1  >>= b1.addActionListener
+    ActionListener.new action3  >>= b3.addActionListener 
+    newContentPane.add b1
+    newContentPane.add b2
+    newContentPane.add b3
+    newContentPane.setOpaque true
+    frame.setContentPane newContentPane
+    frame.pack
+    frame.setVisible true