First commit of partial RosettaCode contents.

Pushing this for testing purposes. Lots of work still needed.

Task/Entropy/Tcl/entropy-2.tcl

@@ -0,0 +1,2 @@
+puts [format "entropy = %.5f" [entropy "1223334444"]]
+puts [format "entropy = %.5f" [entropy "Rosetta Code"]]

Task/Entropy/Tcl/entropy.tcl

@@ -0,0 +1,10 @@
+proc entropy {str} {
+    set log2 [expr log(2)]
+    foreach char [split $str ""] {dict incr counts $char}
+    set entropy 0.0
+    foreach count [dict values $counts] {
+	set freq [expr {$count / double([string length $str])}]
+	set entropy [expr {$entropy - $freq * log($freq)/$log2}]
+    }
+    return $entropy
+}