Added python installed package path for windows
Added observers tests and fixed observers functions
Added doc for observers functions
Added 'removeModelGlobalParam', 'removeFunctionParam' and 'addObserver' functions
Added test for 'removeFunctionParam' and 'removeModelGlobalParam' functions
Added 'removeObserver' function
Added 'clearMonitoring' function
Added 'addFunction' function
Fixed 'clearMonitoring' function
Removed datas dependency for test on observer param
Added tests on observer functions
Fixed 'removeFunctionParam'
Updated tests on simulation function functions

* Removed datas dependency for test on functions parameter
* Added test on (simulation) function function
Fixed CMakeLists for functions parameters test
Cleaned source code
Deleted useless lines
Added 'removeFunction'
Added 'clearModel' function
Optimised getters on function and observers parameters (using boost methods for boost tree)
Added tests on 'removeObserverParam' and 'removeFunctionParam'