re-evaluate directory structure (better isolation of core)

[laroque]

Thoughts include:

• [ ] core/ should be classes which implement wire-protocol and essential behaviors, it should be the entirety of dripline/python/dripline
• [ ] instruments/ should be renamed and moved into dragonfly, it should include broadly useful implementations (the SCPI classes, the ethernet provider, a shell provider, a repeater provider, PostgreSQL interactions, Slack interaction)... The repeater services should potentially just use the base EthernetProvider?
• [ ] bin should still include the most basic of utility functions (basically message_monitor and dripline_agent)... this should include considering moving the generic parser stuff into utilities

[laroque]

deprecation of existing features is going to be delayed, I'm going to go ahead and replace them in dragonfly, then deprecate them from dripline once they are working there; moving this to a far-future milestone

[laroque]

you guessed it... dragonfly