By default the list of profiles is not loaded.

The function updates the corresponding profile, or create a new one if
it doesn't exist.

* Transcoder: 3 ways to add a stream, which call the private function
add( const InputStreamDesc& streamDefinition ).
* This impacts:
     * StreamTranscoder: init with a ProfileDesc instead of a
profileName.
     * OutputEssence (and the subclasses OutputVideo and OutputAudio):
set profile with a ProfileDesc instead of a profileName.
     * swig avTranscoder.i: include Profile because of includes in
output essence source files.
     * avTranscoder app.: can't update the profile with only the
profileName.
     * optionChecker app.: set the profile with the profileDesc.