arv_camera_clear_triggers has potentially unintentional side-effect

[hackel6]

Describe the bug
Using arv_camera_clear_triggers to disable the hardware camera trigger changes the TriggerSelector

To Reproduce

1. set TriggerSelector to some value
2. use arv_camera_clear_triggers
3. check the value of TriggerSelector. if it's the same as (1), repeat with a different value for (1). It should have changed now out from under you.

Expected behavior
Unless it is up to the caller to reset the TriggerSelector after calling arv_camera_clear_triggers, i would expect the triggers to all be cleared, but the TriggerSelector to remain its same value as before the call

Camera description:

• Manufacturer: Lucid
• Model: Triton (TRI245S-MC)
• Interface: GigE

Platform description:

• Aravis version: 0.8.22
• OS: Gentoo (Linux 4.14.178-gentoo #17 SMP)
• Hardware: x86_64

Additional context
Current workaround is to cache the value of TriggerSelector before calling arv_camera_clear_triggers and then reset to back after the call. I'm wondering if it makes sense to move that logic into the arv_camera_clear_triggers method.