Add tee utility

tee.nim

@@ -0,0 +1,15 @@
+import cligen, os, streams
+import common
+
+proc main(files:seq[string]) =
+    var
+        fileStreams:seq[Stream]
+        line = ""
+    for file in files:
+        fileStreams.add(newFileStream(file, fmWrite))
+    while stdin.readLine(line):
+        echo line
+        for fStream in fileStreams:
+            writeLine(fStream, line)
+
+dispatch(main, version=("version", nimbaseVersion))