Add tasks for all the new languages

Task/Leap-year/ERRE/leap-year.erre

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+PROGRAM LEAP_YEAR
+
+FUNCTION LEAP(YR%)
+     LEAP=(YR% MOD 4=0) AND ((YR% MOD 400=0) OR (YR% MOD 100<>0))
+END FUNCTION
+
+BEGIN
+     LOOP
+        INPUT("Enter a year: ",year%)
+        EXIT IF YEAR%=0
+        IF LEAP(year%) THEN
+            PRINT(year%;" is a leap year")
+          ELSE
+            PRINT(year%;" is not a leap year")
+        END IF
+     END LOOP
+END PROGRAM