Export dives to UDDF file

This patch implements exporting dives from Subsurface to UDDF format.
Events and cylinder info are the most remarkable things still missing
from the export.

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add macros for text sizes

This replaces the hardcoded sizes all over the sources.

Make the size in the text_render_options_t a double - With this you can
compile Subsurface with

make CLCFLAGS=-DTEXT_SCALE=1.5

and the fonts in the profile are 50% bigger. Very nice on a high-pixel
density display.

Also remove the unused text_render_options for event text.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>