AVReaderPlugin: refactoring fetchCustomParams

Add a param to simplify the function.
AVReaderPlugin: set the video profile

* Add a profileDesc with the value of OFX video params.
* Add updateVideoProfile() to set the inputStreamVideo.
AVWriterPlugin: refactoring - custom Video/Audio Profile

* Add _videoProfile and _audioProfile to save the custom profileDesc in
the class.
* Add updateVideoProfile() and updateAudioProfile() to update the
corresponding profileDesc depending on the OFX params.
* Simplify ensureVideoIsInit() and initAudio().
AudioVideo: CustomParam - manage OFX Choice

* Get value of OFX Choices for all customParams (for Reader and Writer).
* Add the corresponding FFMPEG Option if the OFX Choice has at least one
child.
AVWriterPlugin: set format profile

* Get value of OFX params related by the format, and create a
ProfileDesc from them.
* Set the ouputFile with the profileDesc.
* ChangeParam: update the value of the format list, depending on the
extension of the output file indicated by the user.
* common/util: add function to get the extension of the given file.
AVReaderPlugin: refactoring - updateVideoProfile

* Need to set video profile at each new render (beginSequenceRender).
* Move setProfile outside of updateVideoProfile (which only update the
video profile).
AVWriterPlugin: add isOutputInit

* Function to get if Output (the ouput file and the transcoder) are
init.
* Throw exception in ensureVideoIsInit and initAudio if Output is not
init.
AVWriterPlugin: refactoring

Remove argument 'AVProcessParams' of the following functions:
     * initOutput
     * initAudio
     * ensureVideoIsInit
AVReaderPlugin: set format profile

* Get value of OFX params related to the format, and create a
ProfileDesc from them.
* Set the inputFile with the profileDesc.
AVReader: remove audio OFX parameters

Reader: No reason to have OFX params related to audio.
AVReaderPlugin: refactoring - update profile

* Get value of OFX parameters related to a profile (format or video) in
the same unique function.
AVReader: add OFX params to display metaData of inputFile

* Get metaData of the input file (currently only the wrapper), and set
the related OFX parameters (MetaData tab).
* Reset these OFX parameters if the input file is not init.
AVWriter: add list of existing format profile

* Like video and audio profile, add a little hack to have nothing
display in detailled group when select an existing format preset.
AVWriterPlugin: refactoring - add comments
AVWriterPlugin: use existing format preset if indicated

The format preset is used for the OutputFile.
AVWriter: fit to new avTranscoder API

* Get format from the file name, from a function in avTranscoder.
* Suppress getExtension in common/util.
AVWriterPlugin: add formatName in custom format Profile

AvTranscoder uses this information to set the AVFormat.
The Profile is invalid and AvTranscoder raises an exception if there is no formatName specified.
AVWriterPlugin: update boost exception in initOutput

* Remove filename: the error is not necessary because of the filename,
so it could be confused...