QmlProfiler: Reduce the amount of useless signals on item selection

By passing signals with identification information of varying accurary
between the different views the event being selected could be changed
while it was selected. By checking the current selection against the
information given in the signal and not reselecting when it matches the
situation is improved.

Also, the selection methods are given more appropriate names. We hardly
ever want to select the "next" event, but rather the "best fitting" one.

Task-number: QTCREATORBUG-11945
Change-Id: I659b4929cb88f4c931a0893aa95a3bc92da5a23b
Reviewed-by: Kai Koehne <kai.koehne@digia.com>