Fix minimizing 3d detector debug window on Windows OS

[papr]

Issue reported on Discord.

Traceback provided via email

2020-11-09 10:01:22,385 - eye0 - [ERROR] launchables.eye: Process Eye0 crashed with trace:
Traceback (most recent call last):
  File "launchables\eye.py", line 731, in eye
  File "site-packages\glfw\__init__.py", line 1772, in poll_events
  File "site-packages\glfw\__init__.py", line 632, in errcheck
  File "site-packages\glfw\__init__.py", line 54, in _reraise
  File "site-packages\glfw\__init__.py", line 611, in callback_wrapper
  File "shared_modules\pupil_detector_plugins\visualizer_3d.py", line 290, in on_resize
  File "shared_modules\gl_utils\trackball.py", line 57, in set_window_size
ZeroDivisionError: float division by zero

• Cause: On Windows OS, the window size becomes zero in both dimensions when then window is minimized
• Fix: Assume a minimum height/width of 1. Precedence.

[romanroibu]

• ✅ reproduced the issue on master
• ✅ confirmed the issue is fixed by this PR