Implemented GetElementInHashMapByID method. Changed 'AddElementToHashMap' to 'AddElementToHashMapWithoutChecks' since it doesn't actually check anyhow if the element with the same ID as inserted is already present in the hash map.
Finally added 'AddOrReplaceElementInHashMap' function, that works as in usual dicts.
Added .DS_Store to gitignore.
Deleted .DS_Store