New node to import known poses for various file formats

[fabiencastan]

Features list

• Import known poses from a JSON file (camera poses and intrinsics)
• Import known poses from XMP (XML) files (camera poses and intrinsics)
• Import known poses from a maya text file .ma (camera poses only).
• [mesh] new remap visibility method without dense sfmData information. Guess visibilities from mesh orientation. It assumes that there is no occultation from non reconstructed elements.
• [mesh] obj loader: fix material index management when combining multiple ones
• [sfm] incremental: optimize input when starting from known poses/landmarks