Trivial s/2021/2022/ on the 2021 templates, plus the updated skyline
image.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Forgot to commit this earlier.

The aspect ratio is still assumed to be 1610, it will be updated when
the information from the organising team is there.

This way people will find this if they search the page for GUADEC.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>

This repository is now more general.

beamerinnertheme: Fix title background size

beamerinnertheme: Fix logo size

The title page's GUADEC logo size was loosely defined, this make its
definition more robust.

Fixes #5

The title page's background size was loosely desfined, this make its
definition more robust.

Fixes #2

Make the content of the title page depend of the page's height instead
of its width, which is needed for it to render nicely on 16/9.

Blocks are drawn as white text on a black background.

Make the frame subtitles use a lighter shade of the current color and
make it smaller so it is more discreet.

Make the structure's color the same as the footer and title page to make
the theme more unified.