Merge branch 'hotfix/3.0.2'
Correctly handle empty newsletter channel selections
Looking for theme templates broke the install routine (see #5210)
Do not separate a style sheet with a font-face selector if the definition is invisible or the media type of the style sheet is "all" (see #5216)
Updated all language files
Version 3.0.3 candidate
Merge branch 'hotfix/3.0.3' into develop

Conflicts:
	system/docs/CHANGELOG.md