LBN, Colours, Single Target Mode and Image Enhancements.

New

• If you only want to inspect a single target, simply set the TARGET environment variable to the object name and run UpTonight. Example: export TARGET="NGC 2359" to calculate and plot only Thor's Helmet.
• Added LBN - Lynds Catalog of Bright Nebulae as a target list.
• Colors can now be set in the config.yaml. See the README.md.

Changes

• Improved object naming in plot. Minor improvements if there is no description or visual magnitude available for a specific object.
• Shrunk the container image from 290MB down to 134MB, reducing unfixable vulnerabilities by three thirds.

Fixes

• Fixed live plots.
• Fixed quoting in f-strings. Thanks to @freedom 👍.