Add SfM Statistics

[theoleplomb]

Description

Add widgets to display SfM statistics.

Features list

• Display stats per view
• Display global SfM stats
• Display landmarks with reprojection errors
• Display features associated to a track but not reconstructed as a 3D landmark

Bugs to fix

• disable display View/Global stats button should close the window
• update of tracks/landmarks are not updated when empty

Based on alicevision/QtAliceVision#5

[natowi]

@theoleplomb Thank you for these nice features.

Here are also some feature requests that are related to your contribution and may be of interest:
#553
#514
#512
Additionally I think it would be interesting to select features in one image and highlight them in the other images