These allow plugins to extend the "Open Project" dialog by adding in support
for new file filters, which appear in the formats drop down list alongside
the existing "QGS Projects" entry.
Custom project open handlers then get first chance at loading project files.
This allows plugins to extend QGIS support by adding integrated support for
opening projects from non QGS/QGZ formats, e.g. allowing users to open
ArcGIS MXD documents or MapInfo WOR Workspaces direct from the project open
dialog.
These non-native projects are also added to the recent projects list and
welcome screen, giving them a truly first-class experience within QGIS.
Sponsored by SLYR
