Test for OK-return-value. (Instead of HTTP_NO_CONTENT.)
Updated documentation.
- Minor typos in ipc_msg.h. (Maybe some of it was even intentional?
  E.g., "mainloop" instead of "main loop"?)
- Added comment for clarification in ipc_msg_client.c, but is my
  understanding correct?
Merge remote-tracking branch 'origin/jnygaard_msgbox_fixing' into kjetilly_msgbox_master_merge
Removed debug options in cmake when building release
Removed asserts around code that needed to run (locks and unlocks mostly).