PHP Hashtable Array: Store key-value pairs in hashed arrays

This class can store key-value pairs in hashed arrays.

It can compute an integer for the index of a hash table entry based on the key string.

The class uses the computed hash index to find the internal array position to find, insert, delete or update the value of the key, as well clear the whole hash table, check if an entry with a key exists, check if the list is empty or get the size of the list.