tuttleHost: fix, OfxhSet is iterable
AudioVideo: fit to avtranscoder v0.4.1
Merge branch 'develop' of https://github.com/tuttleofx/TuttleOFX into dev_AVPluginsAvTranscoder
AudioVideo writer: setProcessMethod of transcoder when instanciate
AudioVideo writer: copyData of buffer into _videoFrame
AudioVideo writer: call getProcessParams again after update format
AudioVideo writer: a preset does not necessary indicate a frame rate
AudioVideo writer: a video profile does not necessary contain a pixel format

* Do not set a pixel format name if the list of supported pixel format
is empty.
* Do not try to get a pixel format if it is not contain in the video
preset.
AudioVideo writer: an audio profile does not necessary contain a sample format

* Do not set a sample format name if the list of supported sample format
is empty.
* Do not try to get a sample format if it is not contain in the audio
preset.
AudioVideo common: refactore setOption of LibAVParams

* Avoid multiple casts.
* Return void instead of bool.
AudioVideo common: LibAVParams class contains an _avContext

* Instanciate the context in constructor.
* Use it when set option.
AudioVideo common: skip unnecessary options when getCorrespondingProfile of LibAVParams

Skip options with a current value equals to their default value.
AudioVideo reader: refactore how to create a rgb pixel