InputFile: refactoring

* Use reference instead of pointer for getStream.
* Use reference instead of pointer for getFormatContext.
InputFile: include AvInputStream instead of forward declaration

Necessary if I want to use the InputStream returned by getStream
function.
AvInputStream: refactoring

Use reference instead of pointer in the constructor.
InputStream Audio and Video: refactoring

Use reference instead of pointer in the constructors.
VideoDesc: refactoring

SetImageParameters by the ImageDesc instead of the complete Image.
AvInputStream: throw if try to read on non-bufferized input stream

Throw runtime_error in readNextPacket if try to read packet on non-
bufferized input stream.
InputStream and InputFile: refactoring

* InputStream: update comment.
* InputFile: add comment.
DataStructures Image: refactoring

Add comments to prepare the field for the template !
Merge branch 'master' of https://github.com/MarcAntoine-Arnaud/avTranscoder into dev_refactoring

Conflicts:
	src/AvTranscoder/InputFile.hpp
	src/AvTranscoder/Transcoder.tcc
Merge pull request #2 from cchampet/dev_refactoring

Refactoring code