Merge pull request #535 from zzottel/master

German docs: added link to privacy help file to main.bb
added A NAME/ID to whitelist in HTMLpurifier. That means we can now make vintage indexes in web pages.
Provide profile tabs opt-out.
Quotes on strings.  Dunno why it worked without.
doc updates
consistency
rename friendica_smarty
remove some code duplication
the sending side of clone syncing of collection/privacy_group information. The receiving side is not yet implemented.
issue #536
issue #536 - move a line so it doesn't interfere
Brain fart. Should really wait until the first cuppa kicks in.
clean up more code duplication
index collection sync info by hash rather than id
limit fields to what we require
fix rename_system_url() for the case of somebody who has no local xchan_url (was cloned from elsewhere and is not primary)
provide os_mkdir to workaround permission issues with php mkdir
Introducing page template Redable (sic). A template for making it easier to read long texts on a wide range of devices. Using rem and em for font sizes and region widths. Regions: aside, content, right_aside and footer. Advised to only use the middle content region as much as possible (but left and right can be used for indexes if you like). Based on the default template. Maybe later I will add some alternative css's.
allow a site to run cron daily at a chosen hour
shield share meta info from markdown processing.