message list navigation buttons

[higuita]

When a message list (in a folder) have lots of
messages, to go to a message we need to press several
times in the next folder page until reaching the
correct message.

if we have about 50 pages, going to any random page is
slow and boring, so roundcube needs a "fast forward"
changes to the navigation: the "top" and "end" buttons
to go to the first and last pages, and a way to write
or change the page number directly (in 50 folder, we
need a easy way to go the page 25)

it could allow writing directly the page number, or add
a + and - sign to change the numbers, and apply then
after 1s without changing

search will make this less important, but its still a
needed thing, as the higher the message number, the
more need to change directly to some page for some reason.

[alec]

Duplicate of #1485235.