ofEvents: initialize member vars, destructors. ofTouchEvent: tapCount->numTaps, etc

- Set initial/default values for ofEvents.
- ofTouchArgs: Changed tapCount -> numTaps to be similar to mouse events
- ofTouchArgs: Added `frame`.
- ofTouchArgs: Changed `time` type to match `ofGetTimeElapsedMillis()`
- ofTouchArgs: Added device id.