kadenz: fixed the bug about infinite loop

The bug will be occur when the page is changed fastly, which will be
inifinite loop.  To fix the bug, added argument `updateHash `is added in
Kadenz.skipToPage().  The hash in URL is update if updateHash is true of
omitted.
kadenz.io: changed key map

The lazer pointer with a feature to turn a page, sends PageUp/PageDown
signals.  The PageUp and PageDown will be mapped as nextStep() and
prevStep() respectively.  furthermore, Space key are added.

The Enter key is conflict to kadenz.pager, because key event is caught
by kadenz.io and kadenz.pager.  Therefore the mechanism which skips to
conflict of the events.