Fixes Solar Control Computer angle being erased in auto tracking (fix #3528)

Fixes #3528.

The  Sun Controller was updating the Solar Control Computer panels direction every sun update, _regardless of the current tracking mode_.
Depending of the position of the auto-tracker and the computer in the _solar_list_, the angle previously set by auto-tracking could then be erased.

The Sun Controller now checks if a Computer is in manual mode before updating manual tracking.