Autoguider: Donuts builtin autoguiding solution

[GuLinux]

Parent task: #33

Use Donuts as guiding/tracking algorithm for a builtin autoguiding solution.

Tasks:

• [ ] add Donuts service (fork a new process?)
• [ ] implement image grabbing hooks and alignment processing
• [ ] Allow to choose either camera ST4 port or telescope for guiding (both through INDI properties)
• [ ] add training phase
• [ ] add correction implementation
• [ ] dithering