Reorganized the project files and CMakeLists

src/lib/include -> include
src/lib/src -> src
src/creator -> tools/creator
CMake configuration related to samples and creator are in separate CMakeLists.

The main CMakeLists adds the c++11 definition (it probably works only for gcc).
Renamed TagDrawer to DrawTag
Merged the two simple filters into one header file

CachingFilter and Estimator are now in Filters.
Estimator is now called AveragingFilter.
Updated the documentation
Fixed warnings
Simplified the API

Kepts only one public header, containing 2 classes:
Chilitags performs the detection on images,
and Chilitags3D uses it to estimate the 3d pose.
They are not functors anymore.
Other utilities such as DrawTag or Codec are accessible via Chilitags.
The persistence filter is embedded in Chilitags, controllable via a parameter.
Moved persistence out of Chilitags' ctor
A boolean controls which tags are 3d-estimated

...instead of testing whether the default marker corners are empty.
The boolean is an optional parameter of the readConfiguration method,
because we don't need it before (without a configuration file, we want to
estimate the position of all the tags)
Moved camera calibration reading into Chilitags3D
Split back the filters into 2 files