Add GUI examples

[iamtesch]

Add simple, clean GUI examples to the repository. Focuses:

• Best-practice separation of control, feedback, and GUI rendering logic
• Explore choices for GUI frameworks
• Use abstracted joystick class for interface
• Have simple examples using these concepts that allow for rock-solid 100Hz + control. Examples: -- Simple visualizer (loads HRDF and names/families) -- Joystick interface to control system (potentially jog arm end effector) -- Display modules on the network -- Video streaming and rotation example?

[rLinks234]

Joystick interface includes:

• HebiModuleController
• Joystick (exposed through hebi.util.input.joystick.Joystick.at_index, which is wrapped nicely in some examples)