add filter options to event debugger

[smeijer]

It should be possible to filter events in the event debugger (under /events, introduced by #167). This way the event log will be less noisy, so it would become easier to extract the data of interest.

To fix this, we can add "dropdown" menu's to the type and name columns, which will allow to enable/disable specific types.

By default, the following events should be filtered out:

mouseenter
mousemove
mouseover
mouseout
mouseleave

pointerover
pointermove
pointerenter
pointerleave
pointerout

[delca85]

If it sounds good to all you I could go with this one.