Colors, agents printing, changes in AreaCell

* include/AreaCell.hpp
+ src/AreaCell.cpp
* Makefile
Class build up. Fields are now private, accessible by getter functions.
Cell can be occupied by agent, pointer available. New constructors.

* include/sim_crowd/Agent.hpp
* include/sim_crowd/AgentBase.hpp
Changed getTypeAbbr() to return 'char' -- in future it should rather
return special enum type.

* include/sim_crowd/types.hpp
Added enum for colors in terminal.

* src/CrowdSimulation.cpp
Color initialization for ncurses.

* src/EventArea.cpp
* src/Unit.cpp
Changes implied by making AreaCell field private.

* src/sim_crowd/World.cpp
Printing agents.