Fix of datastore widget in OpenFLUID-Builder
Added initialize method in OpenFLUID-Builder extensions

* Replaced isReady() const method by non-const initialize() method
* Introduced initialize step in OpenFLUID-Builder extensions launching
system
* Cleaned code

(closes OpenFLUID/openfluid#296)
Minor fixes

* Fixed install path of Builder extensions in CMake macro
* Switched to version 2.0.0~beta12
Added spatial domain structure in OpenFLUID-Builder

* Updated spatial domain widget
* Updated clickable and action label with empty text constructor
* cleaned code

(references OpenFLUID/openfluid#246)
Added spatial domain attributes in OpenFLUID-Builder
    
* Updated spatial domain widget
    
(references OpenFLUID/openfluid#291)
Added layers style and management of spatial domain in OpenFLUID-Builder
   
* Added ability to reorder units classes (for display only)
* Added layers style configuration backup in project file
* Added convenience tools
* Cleaned code

(references OpenFLUID/openfluid#291)
Added simplified map view in OpenFLUID-Builder
   
* Added display and styling of units classes as layers of the map
* Added convenience methods in descriptors
* Cleaned code

(references OpenFLUID/openfluid#291)
Added interactive selection for spatial domain in OpenFLUID-Builder
   
* Added interative selection between map and data
* Refactored map graphics
* Cleaned code

(references OpenFLUID/openfluid#291)
Added edition of spatial attributes in OpenFLUID-Builder
   
* Added in-line edition of single attribute
* Added edition of multiple attributes, 
  with simple operations capabilities (multiplication, addition)
* Cleaned code

(references OpenFLUID/openfluid#291)
Removed deprecated libarchive requirement in CMake configuration
Added removal of spatial units and connections in OpenFLUID-Builder
   
* Added ability to remove a spatial unit
* Added ability to remove a complete class of spatial units
* Added ability to remove a connection between two spatial units
* Added confirmation of any removal in spatial domain
* Added configuration of removals confirmation in preferences dialog

(references OpenFLUID/openfluid#291)
Add of spatial attributes management OpenFLUID-Builder
   
* Added ability to create, rename or remove a spatial attribute
* Cleaned code

(references OpenFLUID/openfluid#291)
Display of spatial events in OpenFLUID-Builder
   
* Added tabular display of events for current units class
* Updated small buttons size in various widgets
  to match the standardized 32x32 size

(references OpenFLUID/openfluid#291)
Fix of ware watchers in OpenFLUID-Builder

* Added delay between ware changes detection and display update
* Fixed refresh of simulators adn observers parameters
* Cleaned code
Fix of clickable URL label in home widget
Fix crash of OpenFLUID-Builder when any project file is wrong formatted

* Updated handling of raised exceptions

(closes OpenFLUID/openfluid#298)
Automatic view fitting for map in OpenFLUID-Builder
   
* Added ability to enable/dosable an automatic view
* Fixed initial view of map when opening project
* Cleaned code

(references OpenFLUID/openfluid#291)
Add of spatial units in  OpenFLUID-Builder
   
* Added ability to create a new spatial units class
* Added ability to create a new spatial unit
* Cleaned code and ui design

(references OpenFLUID/openfluid#291)
Connections between spatial units in OpenFLUID-Builder
   
* Added ability to create connections between spatial units
* Fixed removal of connections

(references OpenFLUID/openfluid#291)
Fix translations and design in simulation run dialog