Modification of the OPENFLUID_SetVariable primitive

Avoiding modifications of past variables
* Removed time parameter in the OPENFLUID_SetVariable primitive
* Updated pass-by-reference of parameters in
  SimulationContributorWare class
* Updated tests and examples

(references #73)
Enhanced primitives for getting values or values lists

* Updated encapsulation of IndexedValue class
* Updated Variables and ValuesBuffer classes
* Added OPENFLUID_GetVariable, OPENFLUID_GetLatestVariable, 
  OPENFLUID_LatestVariables and OPENFLUID_GetVariables primitives
* Updated tests  
* Cleaned code

(closes #73)
Add of stage checking in primitives

(closes #72)
Removal of primitives using pass-by-pointer values

* Removed primitives using pass-by-pointer values
* Adapted tests
* cleaned code

(closes #157)
Refactoring of item type management in signature instances
Removal of instantiation info associated to some simulation elements

* Removed instantiation info class, removed instantiation info attribute
  from some classes
* Updated tests taking into account the removal of instantiation info
* Updated some tests by adding observers in monitoring
* Reduced verbosity of doc build process

(closes #99)
Add of ware parameters check functions

* Fixed management of empty keys
* Added function to check existence of a parameter
* Added function to check if adding a parameter respects xml rules
Redesign of Model and Monitoring modules
Cleaning Monitoring module code
Implementation of move up/down a simulation function
Change ware items background colors

* Added a differentiated background color to item widgets
* Added the default background color to param widgets
Creation of a new set of buttons

* Renamed BuidlerListToolBox to BuilderButtonBox
* Created a new derived class of BuilderButtonBox
* Used the newly created buttons set in wareset items and mapview layers
Implementation of move up/down an observer
Deactivation of first up and last down button
Minor design changes
Change of Model global parameters display
Add of ability to add a custom function parameter

* Added ability to add a parameter for a simulation function, that is not in the signature list of parameters
Improve global parameters merge function

* Fixed multi-level parameters merging
* Added check to merge only non-empty local parameters
Fix checking of insertion of parameter ending with a dot
Change way of adding global parameters

* Added a dialog box to add a global parameter
* Added ability to add a freely-named global parameter