removed some bugs
removed some bugs

SkyQuery now uses meta:host as defaults. Random subscription name as default subscription name is now working. Removing a subscription now removes the channel that was used. Channel name confused with subscription name has been corrected, but defaults allow any code that students might have written from the last few days to continue to use "subscription_name".
No testing has been done on SkyQuery failure paths, but any bugs will result in incomplete error messages, which is acceptable for the moment.
Picolab/pico-engine,Picolab/pico-engine,Picolab/node-pico-engine,Picolab/pico-engine,Picolab/pico-engine,Picolab/node-pico-engine