Fix Save button state on startup
Fix threshold parameters of generators as non mandatory
Cleaning of code

* Removed non longer used code
* Added constness to some advanced descriptor getters
Simplify builder modules updates from Project coordinator
Add of checking of unique IDs

* Added check of unique ModelItem and Observer IDs at project launch
* Prevented duplicate generator IDs

(closes #97)
Removal of BuilderModuleFactory
Cleaning of code

* Removed used of Glib::ustring from ProjectManager
* Removed unused code and headers
* Catched errors by reference
* Added internationalization of ProjectChecker messages
* Reactivated GeoRaster in FluidXDescriptor tests
* Fixed some compilation warnings
* Minor fixes and refactoring

(closes #49)
Add check of unit class of datastore items

(closes #151)