fixes the recently discovered GC memory leaks

This revision is intended as comparison point between the old and the new GC
The used GC can be switched in mmdisp and various statistics will be gathered during
execution (these will be removed/disabled in later revisions)

lib/system/hti.nim

@@ -13,11 +13,19 @@ when defined(NimString):
 else:
   {.pragma: codegenType.}
 
-type # This should be he same as ast.TTypeKind
-     # many enum fields are not used at runtime
+type 
+  # This should be he same as ast.TTypeKind
+  # many enum fields are not used at runtime
   TNimKind = enum
-    tyNone, tyBool, tyChar,
-    tyEmpty, tyArrayConstr, tyNil, tyExpr, tyStmt, tyTypeDesc,
+    tyNone,
+    tyBool,
+    tyChar,
+    tyEmpty,
+    tyArrayConstr,
+    tyNil,
+    tyExpr,
+    tyStmt,
+    tyTypeDesc,
     tyGenericInvokation, # ``T[a, b]`` for types to invoke
     tyGenericBody,       # ``T[a, b, body]`` last parameter is the body
     tyGenericInst,       # ``T[a, b, realInstance]`` instantiated generic type
@@ -30,15 +38,30 @@ type # This should be he same as ast.TTypeKind
     tyTuple,             # WARNING: The compiler uses tyTuple for pure objects!
     tySet,
     tyRange,
-    tyPtr, tyRef,
+    tyPtr,
+    tyRef,
     tyVar,
     tySequence,
     tyProc,
-    tyPointer, tyOpenArray,
-    tyString, tyCString, tyForward,
-    tyInt, tyInt8, tyInt16, tyInt32, tyInt64,
-    tyFloat, tyFloat32, tyFloat64, tyFloat128,
-    tyUInt, tyUInt8, tyUInt16, tyUInt32, tyUInt64,
+    tyPointer,
+    tyOpenArray,
+    tyString,
+    tyCString,
+    tyForward,
+    tyInt,
+    tyInt8,
+    tyInt16,
+    tyInt32,
+    tyInt64,
+    tyFloat,
+    tyFloat32,
+    tyFloat64,
+    tyFloat128,
+    tyUInt,
+    tyUInt8,
+    tyUInt16,
+    tyUInt32,
+    tyUInt64,
     tyBigNum,
 
   TNimNodeKind = enum nkNone, nkSlot, nkList, nkCase