ua: fix doxygen warning
evdev: fix bug, call ui_register() on init
httpd: register UI handlers
celt: module deleted, use opus.so instead
ui: make ui_output() take a formatted string

- minor cleanup in logging
- use ui_output() for interactive output
- avoid using re_printf()
- stdio: added an output_handler (to stderr)
cons: add output handler
Merge remote-tracking branch 'upstream/master'