Fix #47: 'gi' to focus last focused or first text input

Fix #47: 'gi' to focus last focused or first text input

'gi' focuses the last focused or the first -- or the count:th to be precise --
text input of the page. Moreover, after you have focused something with 'gi',
<tab> and <s-tab> switch between only text inputs. That's convenient, because
'gi<tab><tab>' is then equivalent to '3gi'. Instead of trying 'gi' followed by
'<esc>2gi' followed by '<esc>3gi' etc. until you get to the input you want, you
can just type 'gi<tab><tab>' instead.

This required updating vim-like-key-notation to support <s-tab> more reliably.