InputFile: refactore analyse

Split properties nstantiation into 2 lines: better for debugging with
breakpoint and easier to read.
mediaProperty: remove default constructors of Properties

Need to add directives in SWIG interface to explicitly remove vector's
methods which need the default constructor.
AudioProperties: get AVCodec attribute

This removes multi call to avcodec_find_decoder().
AudioProperties: check formatContext/codecContext/codec pointers
AudioProperties: clean format result of getSampleFormatLongName

* small case.
* without point.
AudioProperties: clean getChannelDescription

Clean preprocessor instructions.
VideoProperties: get AVCodec attribute

This removes multi call to avcodec_find_decoder().
VideoProperties: check formatContext/codecContext/codec pointers

* If can't acces the data:
     * return an error (a particular string for example).
     * or throw a runtime exception if no way to return an error.
VideoProperties: use class initialiser list for Rational

Avoid to call default constructor and set each attributes.
mediaProperty: clean output formatting of getDataMap

* Camel case.
* No spaces.
mediaProperty: fillMetadataDictionnary in constructor
SWIG file interface: add EAnalyseLevel enum to binding
SWIG: clean interfaces
pyTests: fit to new way to get media properties

Fix FileProperties for binding: need to add 'avtranscoder' namespace
when return vector of properties (Video, Audio, ...). This enables SWIG
to understand that results of these functions are templates it has
already instanciated in the interface.