Solver manager

Because of #142 (closed) I can't write a proper markdown-based description thus I upload a screenshort ...

• remove former StateBlock notification list
• StateBlock::getState returns by copy
• remove StateBlock::getPtr

src/solver/CMakeLists.txt

+INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR})
+
+# Forward var to parent scope
+
+SET(HDRS_SOLVER ${HDRS_SOLVER}
+                ${CMAKE_CURRENT_SOURCE_DIR}/solver_manager.h PARENT_SCOPE)
+
+SET(SRCS_SOLVER ${SRCS_SOLVER}
+                ${CMAKE_CURRENT_SOURCE_DIR}/solver_manager.cpp PARENT_SCOPE)