Dictionary bug when constructed with capacity param

[Jacek Laskowski]

This code generates AV:

var
  Dct : IDictionary<Integer,Integer>;
begin
  Dct := TCollections.CreateDictionary<Integer, Integer>(10); ← raise AV, THashTable is not initialized

‌

[Stefan Glienke]

fixed initializing and clearing of hashtable (resolves #342)

→ <<cset 2ba450b36a98>>