Release v1.5.0

Changes:

• Rename tgl3d_vertex_shader_simple to tgl_vertex_shader_simple
• Extract anonymous union color in TGLFmt to TGLFmtColor
• Support compilers other than gcc
• Improve windows support
• Implement proper macro hygiene
• Miscellaneous code cleanliness improvements
• Fix bugs in demos
• Rewrite Makefile
• Add github CI