@param insensitive true if the Trie is insensitive to the case of the key.
@param capacity The capacity of the Trie, which is in the worst case
is the total number of characters of all keys stored in the Trie.
The capacity needed is dependent of the shared prefixes of the keys.
For example, a capacity of 6 nodes is required to store keys "foo"
and "bar", but a capacity of only 4 is required to
store "bar" and "bat".
Create a Trie
@param insensitive true if the Trie is insensitive to the case of the key. @param capacity The capacity of the Trie, which is in the worst case is the total number of characters of all keys stored in the Trie. The capacity needed is dependent of the shared prefixes of the keys. For example, a capacity of 6 nodes is required to store keys "foo" and "bar", but a capacity of only 4 is required to store "bar" and "bat".