Add tasks for all the new languages

Task/Topic-variable/Axe/topic-variable.axe

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+3
+Disp *3▶Dec,i

Task/Topic-variable/FreeBASIC/topic-variable.freebasic

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+' FB 1.05.0 Win64
+
+' Three different ways of returning a value from a function
+
+Function Sum (x As Integer, y As Integer) As Integer
+  Sum = x + y  '' using name of function
+End Function
+
+Function Sum2 (x As Integer, y As Integer) As Integer
+  Function = x + y  '' using Function keyword
+End Function
+
+Function Sum3 (x As Integer, y As Integer) As Integer
+  Return x + y  '' using Return keyword which always returns immediately
+End Function
+
+Print Sum (1, 2)
+Print Sum2(2, 3)
+Print Sum3(3, 4)
+Sleep

Task/Topic-variable/Oforth/topic-variable.oforth

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+3 dup sq swap sqrt

Task/Topic-variable/Sidef/topic-variable.sidef

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+say [9,16,25].map {.sqrt};   # prints: [3, 4, 5]