Fix clear() proc for transposition table

Chess/nimfish/nimfishpkg/transpositions.nim

@@ -85,7 +85,8 @@ func clear*(self: var TTable) {.inline.} =
     ## Clears the transposition table
     ## without releasing the memory
     ## associated with it
-    self.data.setLen(0)
+    for i in 0..self.data.high():
+        self.data[i] = TTEntry()
 
 
 func resize*(self: var TTable, newSize: uint64) =

Chess/nimfish/nimfishpkg/uci.nim

@@ -466,6 +466,8 @@ proc startUCISession* =
                             if session.debug:
                                 echo &"info string set TT hash table size to {session.hashTableSize} MiB"
                         of "TTClear":
+                            if session.debug:
+                                echo "info string clearing TT"
                             transpositionTable[].clear()
                         of "Threads":
                             let numWorkers = cmd.value.parseInt()