Additions to KeyComboMatcher

[anhcraft]

A few ideas to the KeyComboMatcher - the one used for matching key combination:

1. Test Commit Key

• It works the same as #commitKey except that it does not change the given key state
• It can be used in conditional statement, and ensure that the method does not cause any update to the argument.
  e.g: testCommitKey(keyState, Key.A)

2. Has Sub-chain

• Given an array of keys representing the heading sub-chain of key combination, returns whether the sub-chain exists
• It can be used to customize the key-combo handling
  e.g: hasSubchain(Key. A, key.B, Key,C, Key.D)