alpha in vertex color is in vtx_ref

[janEntikan]

https://github.com/09th/YABEE/blob/5a9a99bcb9f4375f67e32fe7f679eea6645d80b4/yabee_libs/egg_writer.py#L642

this line should be:

attributes.append('<RGBA> { %f %f %f %f }' % col[:])

or it returns an error

[rdb]

I think some Blender versions use 4 values and some use 3. It should probably check whether Blender returned 4 values or 3 and adjust the output appropriately.