DatasStructures: split in CodedStructures and EssenceStructures
Image / ImageDesc: rename to VideoFrame / VideoFrameDesc
EssenceDesc: rename to CodedDesc
Clean includes

* Remove unused includes.
* Use fast forward declaration if possible.
Merge branch 'master' of https://github.com/avTranscoder/avTranscoder into dev_refactoringStructures
DummyVideo: rename attribute - refactoring

* Rename _VideoFrameDesc to _videoFrameDesc.
clean includes: reorder some includes
DummyAudio: add setFrame

* Can create a dummyVideo, and set its Frame (like DummyVideo).
* When read the next frame of the object, read silent if no specific
Frame was set, or read the data of the Frame specified.
Merge branch 'dev_refactoringStructures' of https://github.com/cchampet/avTranscoder into dev_DummyAudioSetFrame
Merge pull request #29 from cchampet/dev_refactoringStructures

Refactoring & clean
Merge pull request #30 from cchampet/dev_DummyAudioSetFrame

DummyAudio: add setFrame
Audio demultiplexing: fix little endian case

* It was an offset problem.
InputAudio: refactoring readNextFrame with subStream

* Suppress comments.
* Add todo.
VideoDesc: refactoring - rename local variable
VideoDesc: refactoring - reorder includes
AudioDesc: refactoring - reorder includes
Ratio: add default constructor
VideoFrameDesc: add default constructor
OutputVideo: refactoring - rename local variable
Merge pull request #31 from cchampet/dev_subStreams

Fix audio demultiplexing