forums: images wizard
separate files for better readability
initial progress events support
move display functions out of upload function
improvements...
forums images wizard stuff

should be almost final now, except i18n
small debug/improvements
handle dropped images from other tab
error display
i18n
redundant declaration
fixes and i18n for forum images wizard (cherry-picked from master)
Merge branch 'forum-images-wizard' into prod

somehow cherry picked from master
Update url to weather and avalanche bulletins (FR and CH)