Language selection: case-insensitive and system language

Fixed ignoring HTTP_ACCEPT_LANGUAGE tags that had uppercase
characters.

Fixed defining a->language too soon to ever get the system lang
add profile photo app because it is sometimes hard to find. Also doc updates
doc additions
Merge https://github.com/friendica/red into pending_merge
add randprof app and do away with the universally hated chanview-iframe mode. It's gone. Please do not try and bring it back. We are not Diaspora and we have no desire to be like them. ("And they're all made out of ticky-tacky and they all look just the same"). Our profiles do not have to look the same and they won't anyway. We don't have to sugar coat the fact that some of the content in the matrix doesn't look like the rest of the content in the matrix.
Merge pull request #471 from solstag/master

Language selection: case-insensitive and system language