BREAKING CHANGE: set standard to C++11, feat: accessor to breeder ops

Give an access to the operators held by a breeder.
This is needed to design algorithms that dynamically update their
internal parameters during search.
To simplify the interface, we use a returned tuple, and thus upgrade the
C++ standard to C++11.

CMakeLists.txt

@@ -15,6 +15,7 @@ project("ParadisEO")
 
 ## Language
 enable_language(CXX)
+set(CMAKE_CXX_STANDARD 11)
 
 ## Test the presence of a compiler
 if("${CMAKE_CXX_COMPILER}" STREQUAL "" OR "${CMAKE_C_COMPILER}" STREQUAL "")