language chooser: Add a confirm signal

Add a confirm signal, and emit it when the active row is activated
again. This will be use to make Enter go to the next page.

Note that we delay the emission of the signal to an idle to avoid
problems with accessibility.
language page: Go to next when active row is activated twice

This lets you hit Enter twice to select a language and go to the
next page, which is expected behavior in wizard-like UIs like
this.
region chooser: Add a confirm signal

Add a confirm signal, and emit it when the active row is activated
again. This will be use to make Enter go to the next page.

Note that we delay the emission of the signal to an idle to avoid
problems with accessibility.
region page: Go to next when active row is activated twice

 This lets you hit Enter twice to select a region and go to the
 next page, which is expected behavior in wizard-like UIs like
 this.
input chooser: Add a confirm signal

Add a confirm signal, and emit it when the active row is activated
again. This will be use to make Enter go to the next page.

Note that we delay the emission of the signal to an idle to avoid
problems with accessibility.
keyboard page: Go to next when active row is activated twice

This lets you hit Enter twice to select a region and go to the
next page, which is expected behavior in wizard-like UIs like
this.
assistant: Grab focus to the forward button on page change

This arranges things so that hitting Enter will move to the
next page in most cases. We grab the focus before emitting
the GisPage::shown signal, so pages can override this and
put the focus in a better place.
GisPage: Small cleanup

Don't return from void functions.
local account page: Add a confirm signal

Add a confirm signal, and emit it when one of the entries is
activated in a valid page. Also, add a function to forward the
'shown' signal from the main account page.
enterprise account page: Forward the shown signal

Add a function to forward the 'shown' signal from the main
account page. The function puts the focus on the domain
entry.
account page: Go to next when entry is activated

When the account page is valid and one of the entries is activated,
go to the next page. Also, forward the 'shown' signal to the local
or enterprise page, depending on which one is visible. Note that
the activation is not hooked up yet for the enterprise page.
password page: Better focus handling

Move the focus to the password entry when shown, and move to
the next page when an entry is activated and the page contents
are valid.
summary page: Better focus handling

Move the focus to the start button when initially shown.