TouchExplorer - refactoring and a couple of bug fixes

1. Refactored the code to avoid code duplication.

2. Fixed a bug in removing unused pointers from the event.

3. Fixed a bug that was crashing the explorer.

4. Sending hover exit immediately at the end of touch exploration
   gesture rather with a delay.

Change-Id: Ie288cb8090d6fb5e5c715afa6ea5660b17c019e0