AVWriterFactory: update OFX params of 'About' tab

* Update the name of parameters: use name of the lib instead of add a
number.
* Add a label for each of them.
AVWriterPlugin: fix OFX audio param OutputPreset when silent stream

Need to show the OFX parameter when we want a silent stream.
AVWriterPlugin: refactoring functions to update OFX audio parameters

Rename local variables 'flag' to a more specific name.
AVWriterPlugin: clean - inputPixel in ensureVideoIsInit
AVReaderPlugin: clean - dstPixel in beginSequenceRender
AVWriter: rename mainVideoPreset to videoPreset

A mainVideoPreset has sense in case of several video stream...
AVWriter: rename mainAudioPreset to audioMainPreset

Prefix all OFX parameters which concern video by 'video', and the same
for audio.
AVWriter: add audioSelectStream OFX parameter

* OFX parameters for each audio stream.
* By default uncheck: we select all streams of the input audio file.
* If check, display the OFX int parameter to select the stream index.
AVWriter: change audioCopyStream to audioTranscodeStream

By default the OFX param is unchecked (just rewrap the audio streams).
AVWriter: change audioAllChannels to audioSelectChannel

By default the OFX param is unchecked (transcode all channels of audio
stream).
AVWriterPlugin: changedParam if audioStreamIndex

* If the OFX audio parameter audioStreamIndex has changed, update the
audioSelectStream.
* The command line will be easier to write.
AVWriterFactory: update help of OFX audio parameters
AVWriterPlugin: set ProcessMethod of transcoder

* Before process, set a method to the transcoder. This method will
determine how the transcode will be managed (add dummy audio at the end
of an audio stream, etc...).
* Set to Infinity: we stop to transcode when we stop calling
processFrame() in AVWriterProcess.
AVReader: refactoring - updateProfileFromCustomParams

* Remove updateProfileFromCustomParams from AVReader.
* Remove _formatProfile and _videoProfile attributes.
* Add getCorrespondingProfileDesc in CustomParam class.
AVWriter: refactoring - getCustomProfile

* For format, video, and audio profiles:
     * Remove updateXXXProfile() function.
     * Remove _XXXProfile attribute.
     * Add getCustomXXXProfile function.
Host TimeRange: use static_cast instead of lexical_cast

Not expected behavior for double to int.
AudioVideo: do not manage OFX Choice parameter with no choices

Avoid warning of Host when load a plu-in with OFX Choice parameters with
no choices.
AVWriter: correct Licence to License
AVReader: update OFX params of Metadata tab

* Get maps of data from AvTranscoder: we decide how to display these
data in Tuttle.
* Hide OFX String parameters if they are not useful to display the
metadata of the input file.
AVWriterFactory: update OFX param customFps

* Move this OFX parameter to videoGroup tab.
* Set a range and a display range to the OFX Double parameter.
* Hide them if select an existing video preset.