Add multi-texture support to mesh texturing

• store all stages in Interface MVS format by default
• store dense point-cloud as PLY, including all point-views information, etc
• add max-texture-size and multi-texture support to mesh texturing stage
• speedup/improve fix non-manifold mesh algorithm
• unify library/application initialization/destroying
• add python support for reading DMAP and Interface MVS file formats
• account for different pixel center conventions when importing/exporting COLMAP which uses pixel center at (0.5,0.5) instead of (0, 0) as OpenMVS
• add interface to MVSNet, Nerfstudio and RTMV scene formats
• improve interface to Polycam scene format
• speedup PLY load/save
• speedup/improve ray-triangle intersection
• add support for UV coordinates agnostic about orientation
• add support for storing neighbor views information in Interface MVS format
• add support for C++20
• various other fixes