Rename and move Builder descriptor classes

* Moved Builderxxx from guicommon to fluidx namespace
* Renamed Builderxxx to AdvancedxxxDescriptor
* Moved GeneratorSignature and FunctionSignatureRegistry from guicommon to ware namespace
Change management of Observers signatures and check

* Created an ObserverSignatureRegistry class to store Observers plugin signatures
* Created a WaresHelper class to perform checks on Monitoring plugin files
Move Function plugins checking to WaresHelper
Refactor FunctionSignatureRegistry

* Made FunctionSignatureRegistry update himself in constructor, avoiding some explicit updates
* Removed FunctionSignatureRegistrySub class, thaht was used for tests but is no more useful
* Used of built-in example functions as default functions for FunctionSignatureRegistry test cases
Change return parameter of WaresHelper check functions

* Monitoring and Model plugins checking now fill a list of missing IDs, instead of a textual list
Refactor relations management in AdvancedDomainDesc

* Added check of Unit relations when adding a Unit to the domain
* Made const the access to Unit relations to forbid direct modifications
* Added functions to add or remove a relation between two Units, and clear all relations of a Unit with others
Changed threw messages from Builder to Framework
Remove unused "Run" section of project explorer

* Moved run information under "Simulation" section
Merge branch 'rearrange-project-explorer' of https://github.com/alibres/openfluid into alibres-rearrange-project-explorer
Add of an empty Output browser tab

(references #79)
Add of a basic FileChooser for Output browser

(references #79)
Add the path and a reset button to output browser

(references #79)
Removal of plugin file checking when adding an Observer
Merge branch 'remove-addObserver-check' of https://github.com/alibres/openfluid into alibres-remove-addObserver-check
Fixed AdvancedDomainDescriptor::addUnit
* added dfs on graph method
* added check arborescence method
Management of graph arborescence

* Added Edge cleaning flag visited
Reactivation of MapView

* Replaced calls to SimulationBlob and CoreRepository with AdvancedDomainDescriptor

(closes #100)
Cleaning of source code

* Moved observer and function registry classes from ware namespace 
  to machine namespace
* Cleaned unwanted character in #include directive
Replace Output browser with a custom one

* Added ability to choose the application to use for opening a file

(references #79)