New features

Improvements

Report error and early exit if shader source is empty.
utils::slurp_file() now uses the framework’s logging function, ensuring that its error messages will be part of the log file and will be displayed in the console inside the framework.
If the context creation fails, mention to the user the existence of the OpenGL_3.3 branch.
Output all text to the console as UTF-16 on Windows, to properly display non-ASCII characters.
Change the locale to the user-preferred one.
Warn when adding too many textures to an instance of the Node class, and skip adding those extra textures. Each hardware has a different limit as to how many textures can be bound, and going over that limit results in an GL_INVALID_ENUM error which can be hard to understand if one does not know how texture handling works.
Warn and skip when adding a texture of ID 0 to an instance of the Node class. ID 0 is reserved for the “default” texture and no valid texture should have that ID.
Log an error when setting the program for an instance of the Node class with a null pointer, rather than throwing an exception.

Convert paths to UTF-16 on Windows when needed, to ensure that paths containing non-ASCII characters still properly work there.
Do not make attributes constant in SpinConfiguration and OrbitConfiguration, so that the user can use their assignment operator.
Do not append null pointers to the list of children in the Node class; the code previously warned about it but still went ahead with adding it.
Do not make shallow clones for stb and tinyfiledialogs as we check out specific commits, which is not compatible with shallow clones.
Fix the tangent and binormal visualisation shaders: they were being affected by translations, when they should not have, and they used the same model to work matrix as vertices which is usually not valid.