[Feature] succinctness improved
[Feature] InProgress: select any link

Includes related changes made in other files
[Feature] select-any-link feature -  only consider elements in the viewport
[Feature] Use window.scrollY instead of body.scrollTop
[Minor] Removed typo etc
[Feature] InProgres: Select any link

- All links, including those not in the viewport, are considered
for finding the set of matching links, but the one selected first
is the first one in the viewport

- setFakeFocus briefly sets *actual* focus to the element, in order
to benefit from the standard browser feature of ensuring that the
focused element lies in the viewport