Add tasks for all the new languages

Task/Reverse-a-string/Nim/reverse-a-string.nim

@@ -0,0 +1,39 @@
+import unicode
+
+proc reverse(s: var string) =
+  for i in 0 .. s.high div 2:
+    swap(s[i], s[s.high - i])
+
+proc reversed(s: string): string =
+  result = newString(s.len)
+  for i,c in s:
+    result[s.high - i] = c
+
+proc uniReversed(s: string): string =
+  result = newStringOfCap(s.len)
+  var tmp: seq[Rune] = @[]
+  for r in runes(s):
+    tmp.add(r)
+  for i in countdown(tmp.high, 0):
+    result.add(toUtf8(tmp[i]))
+
+proc isComb(r: Rune): bool =
+  (r >=% Rune(0x300) and r <=% Rune(0x36f)) or
+    (r >=% Rune(0x1dc0) and r <=% Rune(0x1dff)) or
+    (r >=% Rune(0x20d0) and r <=% Rune(0x20ff)) or
+    (r >=% Rune(0xfe20) and r <=% Rune(0xfe2f))
+
+proc uniReversedPreserving(s: string): string =
+  result = newStringOfCap(s.len)
+  var tmp: seq[Rune] = @[]
+  for r in runes(s):
+    if isComb(r): tmp.insert(r, tmp.high)
+    else: tmp.add(r)
+  for i in countdown(tmp.high, 0):
+    result.add(toUtf8(tmp[i]))
+
+for str in ["Reverse This!", "as⃝df̅"]:
+  echo "Original string:       ", str
+  echo "Reversed:              ", reversed(str)
+  echo "UniReversed:           ", uniReversed(str)
+  echo "UniReversedPreserving: ", uniReversedPreserving(str)