Add Zmx samples

### Actual behavior

When I try to import some 3rd-party `*.zmx`-files — nothing happen:

- https://github.com/ARSYkun/LSKM
- https://github.com/jegudmunds/refractor_designs

In same time when I try to import `LSST_Baseline_Design_Spiders_Baffles.ZMX` — *Astree* show me *"Unable to Open Zmx file:"*

- https://github.com/lsst-se/LSSTOpticalDesign

### Expected behavior

- Add few samples in Zmx-format;
- Add some checks on after *"Import Zmx file..."* and if format is unsupported:
- Show warning message window with some extra info (file name, format version, etc.);
- Post warning message in terminal output.
- Add some docs about supported file formats.

### REFERENCES

- https://github.com/yiningli/Project_X/tree/master/Database_Files/Zemax_Data
- [`Hubble.zmx`](https://github.com/yiningli/Project_X/blob/master/Database_Files/Zemax_Data/Optical_System_Data/Zemax_Files/Sequential/Telescopes/Hubble.zmx)