Stargo 1.7 | improvements to avoid timeouts

[sterne-jaeger]

Several improvements to avoid timeouts:

• Retrying once reading the motor state to capture timeouts
• Avoid pulse guiding while slewing or parking
• 50ms delay after pulse guiding command to avoid device flooding

Additionally, the tracking speed NONE is removed which overrode the CUSTOM speed button. Meanwhile, the CUSTOM speed is only present if the mount supports custom tracking speeds - which is not the case for Avalon StarGO.