Issue 13: Implement: Object layer scripting
Issue 13: Implement: Object layer scripting

Made Smth_set_tri() use a command through PythonRunCommand.
Also added more error checks to it.

More functions in this file need to be fixed.
tectronics/faint-graphics-editor,tectronics/faint-graphics-editor,tectronics/faint-graphics-editor,tectronics/faint-graphics-editor