Restructure files, make the latex code more modular

Also added a few more section to make beamer and article more
compatible.

VL1/content/VL1_declarations.tex

@@ -0,0 +1,21 @@
+Let's go!
+\begin{haskellcode}
+x :: Int
+x = 3
+
+-- how about this?
+x = 5
+
+-- Int vs Integer
+n :: Integer
+n = 12345678909876543219873409823349873498723498
+
+d :: Double
+d = 5.0
+
+c :: Char
+c = 'k'
+
+s :: String
+s = "Hello, world?"
+\end{haskellcode}