Particle system updates (custom shaders, web support), FreeCAD -> X3D exporter, documentation (exe size, 2D, easy link to API), geometry shader fixes

The post from Castle Engine announces updates to the particle system, including support for custom shaders and web compatibility, as well as improvements related to FreeCAD's X3D exporter and documentation enhancements. It discusses recent developments during August, noting a previous calm period and teasing future Android/iOS compatibility updates from a team member.