OpenSCAD OpenGL Modernization

The project would undertake the necessary code restructuring to facilitate OpenSCAD's transition to rendering with modern OpenGL. An important early step will be adding clear delineation between code paths that result in underlying calls to the two different rendering methods. This groundwork would then grow into developer-controlled flags that would enable the eventual deprecation of the legacy fixed-function calls. Part of the process will involve assessing the readability and testability of higher-level rendering classes and performing refactoring in line with guidance from other developers. Another key area of focus includes assessing and implementing any remaining workarounds needed to replicate the information exchanged between OpenCSG and the legacy rendering classes.