Fix of wrong computation of attribute from VectorLocation method

* Added adapted methods for different geometries
* Corrected related tests
Removal of QtNetwork dependency when including tools.hpp header

* Removed FileDownloader.hpp from tools.hpp
* Refactored FileDownloaderClass

(closes OpenFLUID/openfluid#456)
Allowing update of events in PREPAREDATA stage and later

* Fixes stage checking
* Cleaned code

(closes OpenFLUID/openfluid#464)