Creation of empty ProjectChecker

* Deactivated BuilderModel checking

(references #96)
Implemented ProjectChecker

* Gathered all checks (from Engine::pretestConsistency and BuilderPretestInfo) into ProjectChecker
* Improved check of generators consistency

(references #96)
Add check of monitoring

(references #96)
Reactivation of Model checking

* Moved check of function plugins presence from BuilderModel constructor to EngineProject constructor
* Cleaned code

(references #96)
Add check of units relations at BuilderDomain creation

(references #96)
Add a reverse orientation method for LineStringEntity

* Added About dialog window
Merge branch 'linestringgraph-reverse' of https://github.com/rabotin/openfluid into rabotin-linestringgraph-reverse
set getSize() as const
Add of erase parameter function in WareDescriptor
Merge branch 'WareDesc-eraseParam' of https://github.com/alibres/openfluid into alibres-WareDesc-eraseParam
Fix of ware parameters management

* Added static function to get all parameters as a key-value map, even if key is multi-level
* Improved Fluidx writing, now working with multi-level keys also in function parameters
* Fixed eraseParameter function, now working with multi-level keys
* Added test cases