Easy3D-v2.6.0

Changes

• added Python bindings, with tutorials and test (limited).
  • see Build and install Python bindings
• added a new class LinesDrawable2D for drawing lines in the screen space.
• allowed to enable/disable the clipping plane in the viewer (shortcut: Alt + C).
• for surface mesh, use checkboard as the default texture if the model has texture coordinates.
• made info_to_stdout a parameter in easy3d::initialize().
• made the Qt-related programs compatible with Qt6.
• simplified API of VideoEncoder.
• moved the Signal class from the core module to the util module.
• fixed several typos, bugs, and warnings.

Pre-built binaries are not changed, so you can still use the previous version v2.5.4.