AVWriterPlugin: catch exception if incorrect pixel/sample format

Some host (like Nuke) do not correctly manage list of pixel / sample. To
prevent a wrong use of the plugin, catch exception if the user selects
an correct pixel / sample format (according to the video / audio codec).
AVWriterFactory: update OFX param customFps

* Put the parameter in videoCustomGroupParam.
* Set default value of custom fps to 25.
AVReaderPlugin: fix nbFrames in getTimeDomaine

In some cases, duration and fps give nbFrames rounded up. Use
boost::math::trunc to solve that issue.
AVReaderDefinition: update name of OFX parameters

* Use prefix for all OFX parameters.
* The names are:
     * shorter
     * clearer (no need to know if the parameter comes from an FFmpeg
option or not).
AVReaderDefinition: refactoring names

Get prefix from const string defined in common/util.hpp.
AVWriterDefinition: update name of OFX parameters

* Use prefix for all OFX parameters.
* The names are:
    * shorter
    * clearer (no need to know if the parameter comes from an FFmpeg
option or not).
AVWriterDefinition: refactoring names

* Get prefix from const string defined in common/util.hpp.
* Add label to format, video codec, and audio codec (the label and the
name are now different).
AudioVideo: add PrefixAbout

* Add const string to also have a prefix for OFX parameters in "About"
tab. ("l_", for "library")
* Use it in AVWriterDefinitions.
AVReaderDefinition: add labels

Use them in the Reader Factory.
AVWriterDefinition: add labels

Use them in the Writer Factory.
AVWriter: remove unused OFX param metaDetailledGroup
AudioVideo: fix range of OFX Int Params from FFmpeg options

* Check if max of range is superior to std::numeric_limits<int>::max().
* Check if min of range is superior to std::numeric_limits<int>::min().
AudioVideo: add range to OFX Int2D params from FFmpeg options

Add @todo to manage cases with a different min / max for first and
second int of the parameter.
AVReaderPlugin: suppress unused videoStreamId attribute

* This attribute was confusing with the index of the video stream.
* Prevent errors with odd media file (for example with a video stream id
different from his index in the video streams).
AVWriterPlugin: refactoring

Use const variable instead of numbers (hard to maintain).