Add CMake, doxygen, and coverage test files

Toolchain is now implemented. It generates shared library, unity and coverage
tests, and doxygen documentation.

'build_dev_version.sh' shell script is only here for developement purpose, and
comes with no warranty. It allows to generate html summary of coverage tests
, and cleans the project after building time.

README has been modified, and program is now under GPLv3 license (see COPYING
 file).
sh: add test for cmake, make and make doc

We need to add test if cmake, make and make doc failed.
README: fix markdow typo
Project has been transform to vle extension

Project is now a vle extension. It is developped in C++11, so you must have
modern compiler (GCC >= 4.8).
We added Agent, Scheduler and Event class to manage multi agent systems. We
also added an example with walls and ball.
Headers installation fixed

Installation of extension failed because cmake seach an non existing file.
This bug is now fixed.
New API design

Agent class does not  inherit anymore from vle::devs and is now virtual.
ActiveAgent and PassiveAgent classes are created to be used by final user.
Generalization of Passive agent concept

We have generalized the concept of passive agent: it involved to factorize code
from SimpleWall example to PassiveAgent class.
Coding style modifications

Project has been modified to follow coding style of vle.
Event class improvement

Event class has been improved. Time is now a property of the event. We also
improved the "add_property" function, which now requires rvalue or smart
pointer.
Change iterators type

All iterators have been converted to C++11 auto type
Change to a more complicated example

ball_wall.vpz example has been changed, it is now more complicated (5 walls).
We needed to make some modifications in wall classes because computations were
wrong.
Change README and cmake minimum version
Use of c++11 loops
Clean project

Remove std::cout debug calls.
Change ball port name

Input port name is now 'agent_input' and output port name is 'agent_output'
Create "wallball" executer example

Add executer which created wall and ball with 2 functions 'createWall' and
'createBall'.
Cleaning Event class

Adding typedef to add more readability
Error handling in Event class

We added error handling in the class "Event" (std::map at operation).
Change "handleEvent" function parameter

Parameter has been changed to "Event"
Executer example (continuation)

This example is now the same as ball_wall.vpz one.