Add tasks for all the new languages

Task/Arithmetic-Integer/LFE/arithmetic-integer-1.lfe

@@ -0,0 +1,14 @@
+(defmodule arith
+  (export all))
+
+(defun demo-arith ()
+  (case (: io fread '"Please enter two integers: " '"~d~d")
+    ((tuple 'ok (a b))
+      (: io format '"~p + ~p = ~p~n" (list a b (+ a b)))
+      (: io format '"~p - ~p = ~p~n" (list a b (- a b)))
+      (: io format '"~p * ~p = ~p~n" (list a b (* a b)))
+      (: io format '"~p^~p = ~p~n" (list a b (: math pow a b)))
+      ; div truncates towards zero
+      (: io format '"~p div ~p = ~p~n" (list a b (div a b)))
+      ; rem's result takes the same sign as the first operand
+      (: io format '"~p rem ~p = ~p~n" (list a b (rem a b))))))

Task/Arithmetic-Integer/LFE/arithmetic-integer-2.lfe

@@ -0,0 +1,11 @@
+> (slurp '"arith.lfe")
+#(ok arith)
+> (demo-arith)
+Please enter two integers: 2 8
+2 + 8 = 10
+2 - 8 = -6
+2 * 8 = 16
+2^8 = 256.0
+2 div 8 = 0
+2 rem 8 = 2
+ok