Adding the "Save as" tool button
Fix output browser if output directory is empty

* Added creation of output directory if it doesn't yet exist
Fixing auto-save of a new project
Improve of the examples launch

* Renamed "demo" to "example"
* Catched and displayed errors if no example project is available
* Added a custom icon for the "open example" button

(references #80)
Add of the "restore default" of examples function

(references #80)
Add of the "open example" function in menu bar

(closes #80)
Set "open example" menu visible in Project state

(references #80)
Declaration of produced input data

* Added a DECLARE_PRODUCED_INPUTDATA macro for simulation functions
  signatures
* Updated tests  
* Cleaned code and test datasets 

(closes #77)