update de translation (fix #1487)
fix error message about non-existent submodules
removes obsolete simple main frame"
removes obsolete gradient button
removes some more obsolete simplefrontend only stuff
adds headercheck macros and fixes a lot of discovered issues
properly handle settings exit with changed items, fixes #1695
fix #1697
Merge branch 'master' of git://github.com/renemilk/springlobby

Conflicts:
	src/lsl
don't create torrents/downloads dir as its not used any more by pr-downloader
adds forgotten headercheck template file
update pr-downloader: fix 1698:
don't install any pr-downloader file
Merge remote-tracking branch 'koshi/master'
add option header_check
update pr-downloader
update translations only when required
cleanup cmake "update-translations"
update translations
update lsl
always create translations